### Module 2 Page 6

Question Number. 26. A block slides down a slope. Assuming there is no friction.
Option A. kinetic energy is gained at the same rate as potential energy is lost.
Option B. kinetic energy is gained at a greater rate than potential energy is lost.
Option C. potential energy is gained at a greater rate than kinetic energy is lost.
Correct Answer is. kinetic energy is gained at the same rate as potential energy is lost.
Explanation. KE gained = PE lost (at the same rate).

Question Number. 27. The English unit of mass is.
Option A. the Newton.
Option B. the kilogram.
Option C. the slug.
Explanation. The British unit of mass is the Slug.

Question Number. 28. The SI unit of energy is the.
Option A. Watt (W).
Option B. Pascal (Pa).
Option C. Joule (J).
Explanation. NIL.

Question Number. 29. A 4.5 kW electric motor is 90% efficient. How much energy does it use in 20 seconds?.
Option A. 90 kJ.
Option B. 2.25 kJ.
Option C. 100 kJ.
Explanation. NIL.

Question Number. 30. A pile driver of mass 1000 kg, hits a post 3 m below it. It moves the post 10 mm. Assuming gravity = 10 m/s, what is the kinetic energy of the pile driver?.
Option A. 30 kJ.
Option B. 45 kJ.
Option C. 90 kJ.
Explanation. NIL.

Question Number. 31. The SI unit for work is the.
Option A. Joule.
Option B. Watt.
Option C. horsepower.
Explanation. NIL.

Question Number. 32. What work is done if a force of 100 N moves a body 15 metres?.
Option A. 1500 kJ.
Option B. 1.5 kJ.
Option C. 0.15 mJ.
Explanation. Work = force * distance 100N * 15m = 1500J, or 1.5kJ.

Question Number. 33. Power is the rate of doing work. It is measured in.
Option A. Joules * Seconds.
Option B. Joules/Seconds.
Option C. Watts/Seconds.
Explanation. Power = energy per second = Joules/second.

Question Number. 34. A block slides down a slope. Assuming there is no friction.
Option A. potential energy is gained at a greater rate than kinetic energy is lost.
Option B. kinetic energy is gained at the same rate as potential energy is lost.
Option C. kinetic energy is gained at a greater rate than potential energy is lost.
Correct Answer is. kinetic energy is gained at the same rate as potential energy is lost.
Explanation. KE gained = PE lost (at the same rate).

2.3b. Mechanics – Dynamics.

Question Number. 1. A good refrigerant has a.
Option A. low condensation temperature and high condensation pressure.
Option B. low condensation temperature and low condensation pressure.
Option C. high condensation temperature and low condensation pressure.
Correct Answer is. high condensation temperature and low condensation pressure.
Explanation. NIL.

Question Number. 2. What is the momentum of a ball of mass 2 grams and has a velocity of 10cm/s?.
Option A. 5 kg.m/s.
Option B. 20 kg.m/s.
Option C. 0.0002 kg.m/s.
Explanation. Momentum = mass * velocity. But first convert the numbers to SI. (2 grammes = 2/1000 kg. 10cm = 10/1000 Metres).

Question Number. 3. A gyroscope suffers from apparent wander. This is due to.
Option A. friction on the gimbals and bearings.
Option B. the earth's rotation.
Option C. the aircraft flying along a north/south track.
Correct Answer is. the earth's rotation.
Explanation. Real wander is physical movement from friction in bearings. Apparent wander is due to effect of earth's rotation.

Question Number. 4. The SI unit of momentum is the.
Option A. metre squared (m2).
Option B. kilogram metre per second.
Option C. kilogram / metre (kg/m).
Correct Answer is. kilogram metre per second.
Explanation. Momentum = mass * velocity. So units are kg m/s.

Question Number. 5. Precession in a gyro is.
Option A. proportional to the magnitude of the torque applied.
Option B. proportional to the square of the magnitude of the torque applied.
Option C. inversely proportional to the magnitude of the torques applied.
Correct Answer is. proportional to the magnitude of the torque applied.
Explanation. NIL.

Question Number. 6. A gyro with a fixed point free to rotate in three axis is.
Option A. a tied gyro.
Option B. a space gyro.
Option C. an earth gyro.
Correct Answer is. a tied gyro.
Explanation. If the gyro is fixed to one point, it is a tied gyro. (An earth gyro is 'tied' specifically to an earth reference point).

Question Number. 7. What type of friction requires the greatest force to overcome it?.
Option A. Dynamic friction.
Option B. Static friction.
Option C. Rolling friction.
Explanation. Static friction (sometimes called 'stiction') is the greatest friction. Followed by Dynamic and Rolling respectively.

Question Number. 8. If a gyro is constrained to an external reference and has three degrees of freedom it is.
Option A. a tied gyro.
Option B. an earth gyro.
Option C. a space gyro.
Correct Answer is. a tied gyro.
Explanation. A tied gyro has one axis fixed to a point (in space or on earth). An earth gyro is a tied gyro but with one axis specifically fixed to a reference on earth.

Question Number. 9. The point at which an applied force overcomes friction and an object begins to move is the co-efficient of.
Option A. limiting friction.
Option B. static friction.
Option C. kinetic friction.
Explanation. NIL.

Question Number. 10. The amount a gyro precesses when a torque is applied is.
Option A. proportional to the torque.
Option B. inversely proportional to the torque.
Option C. proportional to the square of the torque.
Correct Answer is. proportional to the torque.
Explanation. NIL.

Question Number. 11. The gyroscopic principle is based upon.
Option A. Newton’s 3rd Law.
Option B. Newton’s 2nd Law.
Option C. Newton’s 1st Law.
Correct Answer is. Newton’s 1st Law.
Explanation. Newton's First Law is also called the 'Inertia Law'.

Question Number. 12. A mass of 20kg produces a momentum of 300kgm/s. What is the Kinetic energy?.
Option A. 3250 Joules.
Option B. 2250 Joules.
Option C. 0.25 Kilojoules.
Explanation. Momentum = MV, 300 = 20V, V = 15. KE = 1/2MV2 = 1/2*20*15*15 = 2250J.

Question Number. 13. A motorcycle of mass 400kg is moving at a velocity of 8m/s. Calculate its momentum.
Option A. 3200 kgm/s.
Option B. 50 kgm/s.
Option C. 320 kgm/s.
Explanation. Momentum = mass * velocity.

Question Number. 14. If the speed of a gyro is increased, the force required to precess the gyro is.
Option A. increased.
Option B. remains the same.
Option C. decreased.
Explanation. Rigidity increases with RPM.

2.4a. Mechanics - Fluid Dynamics.

Question Number. 1. The specific gravity of a substance is calculated by.
Option A. density of the body squared multiplied by the density of water.
Option B. the density of the body divided by the density of water.
Option C. density of the body multiplied by the density of water.
Correct Answer is. the density of the body divided by the density of water.
Explanation. Specific' always means 'per' something or divide by.

Question Number. 2. The SI unit of density is the.
Option A. kilogram per cubic metre (kg/m3).
Option B. Pascal (Pa).
Option C. cubic metre (m3).
Correct Answer is. kilogram per cubic metre (kg/m3).
Explanation. NIL.

Question Number. 3. Relative density is.
Option A. density of water x density of medium.
Option B. density of water/density of medium.
Option C. density of medium/density of water.
Correct Answer is. density of medium/density of water.
Explanation. NIL.

Question Number. 4. The standard for measuring density is.
Option A. 0 °C and 760 mm of mercury.
Option B. -20 °C and 700 mm of mercury.
Option C. +20 °C and 760 mm of mercury.
Correct Answer is. 0 °C and 760 mm of mercury.
Explanation. STP.

Question Number. 5. 1kg of water is heated from 0 °C to 2 °C. Its volume will.
Option A. decrease.
Option B. stay the same.
Option C. increase.
Explanation. When ice melts, its volume decreases up to 3 °C.

Question Number. 6. A pilot requests 9.2 tonnes of fuel. The bowser driver reports to the pilot that the specific gravity is 0.8, what will the uplift be?.
Option A. 7360 litres.
Option B. 11500 litres.
Option C. 9200 litres.
Explanation. 1 litre of water has a mass of 1kg. 1000 litres of water has a mass of 1 metric tonne. 9.2 tonnes of water is 9200 litres. But fuel is lighter than water (0.8x) so the uplift will be more than 9200 litres.

Question Number. 7. Specific gravity.
Option A. is measured in kg/m2.
Option B. is measured in kg/m3.
Option C. has no units.
Correct Answer is. has no units.
Explanation. Specific gravity is the density of the fluid divided by the density of water. Since both have the same units (kg/m3) they cancel - hence, no units.

Question Number. 8. The standard temperature and pressure for measuring the density of liquids is.
Option A. 15 °C and 760 mmHg.
Option B. 0 °C and 760 mmHg.
Option C. 4 °C and 760 mmHg.
Correct Answer is. 4 °C and 760 mmHg.
Explanation. Since water is most dense at 4 °C (1000 kg/m3), this is used as the standard temperature. When working out specific gravity, the fluid in question must also be 4 °C. (But remember it is 0 °C for gases, and room temp - 20 °C - for barometers).

Question Number. 9. The standard temperature and pressure for measuring the volume of liquids and solids is.
Option A. 20 °C and 700 mmHg.
Option B. 20 °C and 760 mmHg.
Option C. 0 °C and 760 mmHg.
Correct Answer is. 20 °C and 760 mmHg.
Explanation. Since the volume of solids and gases changes with temperature (and a lesser amount with pressure) the standard for measuring volume is 20 °C. (room temp.) and 760mmHg (standard sea level atmospheric pressure).

Question Number. 10. Given that 1 cubic foot of water weighs 62.4 lbs and the specific gravity of fuel is 0.81, what is the weight of 10 cubic foot of fuel?.
Option A. 402.8 lbs.
Option B. 505.4 lbs.
Option C. 770.3 lbs.
Explanation. 10 * 62.4 = 624. 624 * 081 =.

Question Number. 11. At what temperature does water have the greatest density?.
Option A. 0 °C.
Option B. 100 °C.
Option C. 4 °C.
Explanation. Solidification begins at 4 °C when cooling.

Question Number. 12. The specific gravity of methylated spirit is 0.8. Its density is.
Option A. 800 g/m3.
Option B. 800 kg/m3.
Option C. 80 kg/m3.
Explanation. sg = density of fluid/density of water density of fluid = sg * density of water density of water = 1000 kg/m3.

Question Number. 13. The density of Cu is 8,900kg/m3. What is its relative density?.
Option A. 890.
Option B. 8.9.
Option C. 89.
Explanation. rel. density = density of substance/density of water= 8900/1000.

2.4b. Mechanics - Fluid Dynamics.
Question Number. 1. Atmospheric pressure at ISA conditions is.
Option A. 1013 pa.
Option B. 1013 bar.
Option C. 1013 mBar.
Explanation. NIL.

Question Number. 2. Convert 220 gallons to litres.
Option A. 1000 litres.
Option B. 48.4 litres.
Option C. 500 litres.
Explanation. Imagine how many times a large coke bottle goes into a normal engine oil container (about 4 (and a bit)), then * 220. http://www.metric-conversions.org/

Question Number. 3. The SI unit of pressure is the.
Option A. Newton per metre squared (N/m2).
Option B. Cubic metre (m3).
Option C. kilogram per metre cubed (kg/m3).
Correct Answer is. Newton per metre squared (N/m2).
Explanation. Pressure = force / area. So units of pressure is Newtons / square metre (or better known as Pascals).

Question Number. 4. A gauge indicates 15 PSIG. What is the absolute pressure?.
Option A. 30 PSI.
Option B. 0.3 PSI.
Option C. Zero PSI.
Explanation. Absolute pressure = gauge pressure + atmospheric pressure. (The G in PSIG means 'gauge') Atmospheric pressure varies slightly so is not always the 14.7 PSI of the ISA. http://en.wikipedia.org/wiki/Pound-force_per_square_inch

Question Number. 5. Water is most dense at.
Option A. -4 °C.
Option B. 0 °C.
Option C. +4 °C.
Explanation. As water cools, the molecules begin to crystallise at 4 °C. Crystallized water (i.e. ice) has a greater volume than liquid water and therefore less density (that is why ice floats). http://www.physicalgeography.net/fundamentals/8a.html

Question Number. 6. Viscosity can be described as.
Option A. Newton's 1st law of motion.
Option B. fluids flowing in a straight line.
Option C. the internal resistance for a fluid to flow.
Correct Answer is. the internal resistance for a fluid to flow.
Explanation. Viscosity is opposition to flow of a fluid.

Question Number. 7. How much lift is produced on a wing can be derived from.
Option A. Bernoulli's Theorem.
Option C. Charles law.
Explanation. Bernoulli's theorem.

Question Number. 8. Pressure in a pipe is.
Option A. force per unit area.
Option B. mass divided by cross-sectional area.
Option C. weight per unit area.
Correct Answer is. force per unit area.
Explanation. NIL.

3a. Thermodynamics.

Question Number. 1. Convert 25 degrees centigrade to fahrenheit.
Option A. 57.
Option B. 77.
Option C. -7.
Explanation. (25*1.8)+32= 77.

Question Number. 2. You are at the north pole where the temperature is minus 50 °C below freezing. What sort of thermometer would you use to measure it?.
Option A. Water.
Option B. Alcohol.
Option C. Mercury.
Explanation. NIL.

Question Number. 3. Convert 15 °C to °F.
Option A. 37 °F.
Option B. 59 °F.
Option C. 62 °F.
Explanation. ISA sea level temperature 15 °C = 59 °F.

Question Number. 4. 1 degree rise on the centigrade scale will cause a.
Option A. 1.8 degree rise in Fahrenheit.
Option B. 33 degree rise in Fahrenheit.
Option C. 0.911 degree rise in Fahrenheit.
Correct Answer is. 1.8 degree rise in Fahrenheit.
Explanation. NIL.

Question Number. 5. 1 calorie is equal to.
Option A. 4 J.
Option B. 40 J.
Option C. 400 J.
Explanation. NIL.

Question Number. 6. 1 BTU equals.
Option A. 1055 Joules.
Option B. 1055 Calorie.
Option C. 1055 kJ.
Explanation. NIL.

Question Number. 7. Temperature is a measure of.
Option A. the amount of friction produced by two mating surfaces.
Option B. the amount of vibration of molecules.
Option C. the heat energy of particles.
Correct Answer is. the amount of vibration of molecules.
Explanation. Heat energy applied to an object does not necessarily increase temperature (eg. when melting or evaporating).

Question Number. 8. What temperature scale is used with the combined gas law?.
Option A. Absolute.
Option B. Fahrenheit.
Option C. Celsius.
Explanation. Kelvin (absolute scale) is always used with the combined gas law equation.";.

Question Number. 9. What is 1 btu/lb in joules per kilogram?.
Option A. 2326 j/kg.
Option B. 4128 j/kg.
Option C. 9.18 j/kg.
Explanation. This is referring to specific energy content (J/kg or Btu/lb) of fuel. 1 btu = 1055 J. 1 lb = 2.2 kg. Therefore 1 btu = 2326 J/kg.

Question Number. 10. 1 CHU = Centigrade Heat Unit = 1400 ft lbs =energy to raise.
Option A. 1 lb of water by 1 °F.
Option B. 1 kg of water by 1 °C.
Option C. 1 lb of water by 1 °C.
Correct Answer is. 1 lb of water by 1 °C.
Explanation. 1 CHU is the heat required to raise 1 lb of water 1 degree Centigrade (=1.8 BTU).

Question Number. 11. 1 BTU = 778 ft lbs which is the energy required to raise the temperature of.
Option A. 1 lb of water by 1 °F.
Option B. 1 kg of water by 1 °F.
Option C. 1 lb of water by 1 °C.
Correct Answer is. 1 lb of water by 1 °F.
Explanation. 1 BTU is the heat required to raise 1 lb of water 1 degree Fahrenheit.

Question Number. 12. A temperature of 41 degrees Fahrenheit is, in Centigrade.
Option A. 9 degrees.
Option B. 5 degrees.
Option C. 7 degrees.
Explanation. C = 5/9(F-32).

Question Number. 13. Heat is described as.
Option A. a high temperature.
Option B. energy in transit.
Option C. the stored energy in a hot body.
Correct Answer is. energy in transit.
Explanation. Heat is a type of transfer of energy which increases the kinetic energy of the molecules within a body.

Question Number. 14. 600K is equal to.
Option A. 853 °C.
Option B. 873 °C.
Option C. 326.85 °C.
Explanation. Subtract 273.15.

Question Number. 15. When gases change temperature/pressure, the scale used is.
Option A. Kelvin.
Option B. degrees Fahrenheit.
Explanation. Always use the Kelvin scale in thermodynamics.

Question Number. 16. Convert 100 °C to Kelvin.
Option A. 173 K.
Option B. 373 K.
Option C. 273 K.
Explanation. Degrees C to Kelvin - just add 273.

Question Number. 17. -40 °C in Fahrenheit is.
Option A. 72 °F.
Option B. 8 °F.
Option C. -40 °F.
Explanation. °F = 1.8 °C + 32 1.8(-40) + 32 = -40 °F. Please do not report this as an error.

Question Number. 18. Absolute zero is.
Option A. 0 °C.
Option B. 273.15 K.
Option C. -273.15 °C.
Explanation. Absolute zero is - 273.15 degrees Celsius.

Question Number. 19. One degree increment on the Centigrade scale is equal to what increment on the Fahrenheit scale?.
Option A. 1.8 °F.
Option B. 33 °F.
Option C. 12 °F.
Explanation. A change of' 1 degree C. it is equal to 'a change of' 1.8 degree F.

Question Number. 20. Transfer of heat from a hot area to a cold area is.
Option A. conduction.
Option B. convection.
Explanation. Convection is a transfer of 'matter' from one place to another. Radiation is a system which heats up anything in its path. but heat is not 'transferred'.

Question Number. 21. Fahrenheit may be converted to Celsius by using the equation.
Option A. °C = 5/9 * ( °F - 32).
Option B. °C = 5/9 * °F - 32.
Option C. °C = 9/5 * °F + 32.
Correct Answer is. °C = 5/9 * ( °F - 32).
Explanation. °C = 5/9( °F-32). °F = 9/5 °F + 32.

Question Number. 22. What is 1 BTU/lb in joules per kilogram?.
Option A. 4128 joules per kilogram.
Option B. 9.18 joules per kilogram.
Option C. 2326 joules per kilogram.
Correct Answer is. 2326 joules per kilogram.
Explanation. 1 BTU/lb = 2326 j/kg. This is referring to heat of combustion of fuel.

Question Number. 23. Celsius to Fahrenheit is calculated by.
Option A. (9/5 * °C) + 32.
Option B. (5/9 * °C) + 32.
Option C. (5/9 + 32) + °C.
Correct Answer is. (9/5 * °C) + 32.
Explanation. Remember standard sea level temperature is 15 °C and 59F. Make °C = 15 on each formula above, and see which comes out at 59 °F".

Question Number. 24. The percentage of nitrogen in air is approximately.
Option A. 0.62.
Option B. 0.21.
Option C. 0.78.
Explanation. NIL.

Question Number. 25. When a system undergoes a complete cycle where the net heat supplied is equal to work done plus a change in internal energy - this is known as.
Option A. 2nd Law of thermodynamics.
Option B. First law of thermodynamics.
Option C. Ideal Gas law.
Correct Answer is. First law of thermodynamics.
Explanation. NIL.

Question Number. 26. In a heat pump.
Option A. the evaporator gains heat during the heating cycle.
Option B. the condenser always loses heat.
Option C. the pump operates in both directions.
Correct Answer is. the pump operates in both directions.
Explanation. NIL.

Question Number. 27. What is -28 °C on the Kelvin scale?.
Option A. 245 K.
Option B. 18 K.
Option C. 291 K.
Explanation. -28 + 273 = 245.

Question Number. 28. When water freezes, heat energy is.
Option A. absorbed.
Option B. retained.
Option C. released.
Explanation. Freezing is 'exothermic'.

Question Number. 29. 842 degrees Fahrenheit is equal to.
Option A. 450 Degrees Celsius.
Option B. 400 Degrees Celsius.
Option C. 232.2 degrees Celsius.
Correct Answer is. 450 Degrees Celsius.
Explanation. C = 5/9(F - 32).

Question Number. 30. For a fixed mass of water at sea level ISA conditions and at 10,000ft.
Option A. the water will boil at a lower temperature than sea level.
Option B. the water will boil at the same temperature as sea level.
Option C. the water will boil at a higher temperature than sea level.
Correct Answer is. the water will boil at a lower temperature than sea level.
Explanation. As pressure drops, so does the boiling temperature.

Question Number. 31. Dew point is.
Option A. the temperature at which condensation actually occurs.
Option B. the temperature below which condensation occurs.
Option C. the temperature above which condensation occurs.
Correct Answer is. the temperature below which condensation occurs.
Explanation. NIL.

Question Number. 32. By adding impurities to water.
Option A. the melting point will increase and the boiling point decrease.
Option B. there will be no effect to the melting and boiling points.
Option C. the melting point will decrease and the boiling point will increase.
Correct Answer is. the melting point will decrease and the boiling point will increase.
Explanation. NIL.

Question Number. 33. Which type of circuit is used when the temperature of the source has insufficient heat for thermocouple application?.
Option A. thermistor.
Option B. temperature bulb.
Option C. balanced bridge.
Explanation. NIL.

Question Number. 34. Four pounds of gas at a temperature of 17 °C is heated to 89 °C. The specific heat at constant pressure and constant volume are 0.2404 and 0.1718 respectively. Find the heat absorbed by the gas at constant pressure and at constant volume.
Option A. 70.1 C.H.U. and 50 C.H.U.
Option B. 49.5 C.H.U. and 69 C.H.U.
Option C. 69.2 C.H.U. and 49.5 C.H.U.
Correct Answer is. 69.2 C.H.U. and 49.5 C.H.U.
Explanation. Q = mC(T2 -T1), 4 * 0.2404 * 72 = 69.2 CHU, and 4 * 0.1718 * 72 = 49.5 CHU.

Question Number. 35. In 'standard conditions' what is the standard for measurement of volume and density of a gas?.
Option A. 0 °C and 760mm of Mercury.
Option B. 20 °C and 700mm of Mercury.
Option C. 20 °C and 760mm of Mercury.
Correct Answer is. 0 °C and 760mm of Mercury.
Explanation. STP also applies to solids and liquids.

Question Number. 36. In 'standard conditions' what is the standard for measurement of volume and density of a liquid or solid?.
Option A. 20 °C and 760mm of Mercury.
Option B. 0 °C and 760mm of Mercury.
Option C. 20 °C and 700mm of Mercury.
Correct Answer is. 0 °C and 760mm of Mercury.
Explanation. NIL.

Question Number. 37. 842 Degrees Fahrenheit is equal to.
Option A. 450 Degrees Celsius.
Option B. 232.2 Degrees Celsius.
Option C. 400 Degrees Celsius.
Correct Answer is. 450 Degrees Celsius.
Explanation. NIL.

Question Number. 38. Which of the following 2 points are equal?.
Option A. -32 °C and 0 °F.
Option B. 40 °C and 40 °F.
Option C. -40 °C and -40 °F.
Correct Answer is. -40 °C and -40 °F.
Explanation. NIL.

Question Number. 39. What is 100 Degrees Centigrade in Fahrenheit?.
Option A. 30 Degrees.
Option B. 148 Degrees.
Option C. 212 Degrees.
Explanation. NIL.

Question Number. 40. The absolute temperature scale that has the same increments as the Fahrenheit scale is the.
Option A. Rankin scale.
Option B. Kelvin scale.
Option C. Celsius scale.
Explanation. NIL.

Question Number. 41. The absolute temperature scale that has the same increments as the Celsius scale is the.
Option A. Rankin scale.
Option B. Kelvin scale.
Option C. Fahrenheit scale.
Explanation. NIL.

3b. Thermodynamics.

Question Number. 1. For a heat pump to internally heat it uses a.
Option A. inside evaporator.
Option B. inside condenser.
Option C. outside condenser.
Explanation. NIL. http://en.wikipedia.org/wiki/Heat_pump

Question Number. 2. The heat required to change a liquid to a gas is called the heat of.
Option A. condensation.
Option B. fusion.
Option C. vapourisation.
Explanation. Liquid to gas is vapourisation. Solid to liquid is fusion (another term for melting - like fusion welding).

Question Number. 3. What is the SI units for specific heat capacity?.
Option A. Jkg-1k-1.
Option B. J/S/C.
Option C. J/ kg.
Explanation. NIL.

Question Number. 4. The most common refrigerants are.
Option A. water, ammonia, freon.
Option B. water, freon, carbon dioxide.
Option C. ammonia, freon, methyl bromide.
Correct Answer is. water, ammonia, freon.
Explanation. All are refrigerants - water is used in cooling towers. Methyl bromide is almost completely phased out due to safety and environmental reasons. Carbon dioxide has been used but no more due to availability of better refrigerants such as ammonia.

Question Number. 5. How is heat transferred in a vacuum?.
Option A. Convection.
Option B. Conduction.
Explanation. NIL.

Question Number. 6. The specific heat capacity of a gas heated at constant pressure, when compared to the specific heat capacity of a gas heated at constant volume, is.
Option A. more.
Option B. less.
Option C. the same.
Explanation. Cp is slightly higher than Cv. Usually it only applies to gases. For example the Cp for air is 1.4 times more than its Cv.

Question Number. 7. Adiabatic compression is when.
Option A. no heat is lost or gained.
Option B. kinetic energy is gained.
Option C. heat is given off to the surroundings.
Correct Answer is. no heat is lost or gained.
Explanation. NIL.

Question Number. 8. The heat required to change a solid to a liquid is called the heat of.
Option A. vapourisation.
Option B. condensation.
Option C. fusion.
Explanation. Another word for melting is 'fusion' (as in fusion welding - or... 'a fuse').

Question Number. 9. Latent heat is the.
Option A. heat required to raise the temperature of a body by 1 °C.
Option B. heat required to raise 1kg of matter by 1K.
Option C. heat required to change the state of a body.
Correct Answer is. heat required to change the state of a body.
Explanation. Latent' means 'hidden'. It is the heat energy required to change the state (melt or vapourise). No rise in temperature is pruduced whilst doing so - hence the 'hidden' bit.

Question Number. 10. The intensity of radiated heat is.
Option A. inversely proportional to the square of the distance from the source of the heat.
Option B. not effected by the distance from the source of the heat.
Option C. directly proportional to distance from the source of the heat.
Correct Answer is. inversely proportional to the square of the distance from the source of the heat.
Explanation. Like most such things, intensity of heat, gravity, magnetism etc. - they all reduce with the square of the distance (i.e. double the distance and the intensity is 1/4).

Question Number. 11. As a block of ice is melted (to 4 °C). Its volume.
Option A. remains the same.
Option B. decreases.
Option C. increases.
Explanation. Ice expands as it gets colder - which is why water pipes burst if they freeze.

Question Number. 12. A good refrigerant has.
Option A. high condensing pressure, low evaporating temperature.
Option B. high condensing pressure, high evaporating temperature.
Option C. low condensing pressure, low vaporating temperature.
Correct Answer is. low condensing pressure, low vaporating temperature.
Explanation. The refrigerant must evaporate at lower temperature than the 'cold space' and must condense at a relatively high temperature, with a low compression level.

Question Number. 13. In a heat pump.
Option A. In a heat pump.
Option B. the condenser loses heat.
Option C. flow across the condenser is always in one direction.
Correct Answer is. the condenser loses heat.
Explanation. Heat pumps can be used to cool as well as heat. Refrigerant flow changes direction respectively, but the condensor always rejects the heat.

Question Number. 14. Charles' Law states that.
Option A. volume varies inversely with temperature.
Option B. volume varies directly with temperature.
Option C. volume equals pressure * temperature.
Correct Answer is. volume varies directly with temperature.
Explanation. NIL. http://en.wikipedia.org/wiki/Charles_law

Question Number. 15. Boyle's law states that.
Option A. pressure equals temperature divided by volume.
Option B. pressure varies directly with volume.
Option C. pressure varies inversely with volume.
Correct Answer is. pressure varies inversely with volume.
Explanation. Pressure rises, volume decreases.

Question Number. 16. Convection does not occur in.
Option A. liquids.
Option B. liquids.
Option C. solids.
Explanation. The medium must 'flow' for conduction to take place.

Question Number. 17. A process where volume does not change is.
Option A. isochoric.
Option B. isobaric.
Option C. isothermic.
Explanation. NIL.

Question Number. 18. A process where heat is not transferred to or from a gas is.
Option B. isochoric.
Option C. isobaric.
Explanation. NIL.

Question Number. 19. A process where pressure does not change is known as.
Option A. isochoric.
Option B. isothermic.
Option C. isobaric.
Explanation. Iso' means equal. 'bar' is pressure.

Question Number. 20. When a liquid is heated, it expands.
Option A. more than a solid.
Option B. less than a solid.
Option C. more than a gas.
Correct Answer is. more than a solid.
Explanation. Generally speaking, liquids have a greater coefficient of thermal expansion than solids.

Question Number. 21. If pressure on a liquid increases, whilst temperature is held constant, the volume will.
Option A. decrease.
Option B. remain constant.
Option C. increase.
Explanation. Liquids are incompressible.

Question Number. 22. A process where temperature remains the same is known as.
Option A. isobaric.
Option B. isochoric.
Option C. isothermic.
Explanation. Iso' means equal. 'Thermal' is temperature.

Question Number. 23. What is descriptive of Boyle's Law? (P=Pressure, V=Volume, T=Temperature).
Option A. P is proportional to 1/T.
Option B. P is proportional to 1/V.
Option C. P is proportional to T.
Correct Answer is. P is proportional to 1/V.
Explanation. Pressure (P) is inversely proportional to volume (V).

Question Number. 24. A compressor increases.
Option A. kinetic energy.
Option B. potential energy.
Option C. moving energy.
Explanation. Compressed air is a form of 'potential energy'.

Question Number. 25. P1 * V1 / T1 = P2 * V2 / T2 is (P=Pressure, V=Volume, T=Temperature).
Option A. Ideal gas law.
Option B. Charles' law.
Option C. Boyle's law.
Correct Answer is. Ideal gas law.
Explanation. NIL.

Question Number. 26. V1 / T1 = V2 / T2 at a constant pressure is (P=Pressure, V=Volume, T=Temperature).
Option A. ideal gas law.
Option B. Boyle's law.
Option C. Charles' law.
Explanation. NIL.

Question Number. 27. P1 * V1 = P2 * V2 at a constant temperature is (P=Pressure, V=Volume, T=Temperature).
Option A. Boyle's law.
Option B. ideal gas law.
Option C. Charles' law.
Explanation. NIL.

Question Number. 28. The atmosphere's temperature changes at a rate of -1.98 °C per 1000 ft up to 36,000 ft where it remains constant at.
Option A. -56 °F.
Option B. -52 °C.
Option C. -56 °C.
Explanation. The troposphere is a constant -56 degrees C.

Question Number. 29. A process where heat is given off to its surroundings is called.
Option A. isothermal.
Option C. isobaric.
Explanation. Adiabatic' is a process where NO heat is given off to its surroundings. Isobaric is constant pressure. Isothermal, to keep constant temperature must give off heat as it is compressed.

Question Number. 30. A body which is allowed to expand when heated, expands past the pressure imposed on it and.
Option A. a force is produced.
Option B. nothing will happen.
Option C. work is done.
Correct Answer is. work is done.
Explanation. Work is done when it exerts a force and moves (work = force x distance). Yes, a force is produced but this is not the whole story.

Question Number. 31. The quantity of heat developed by burning 1 kg of fuel is known as.
Option B. latent heat.
Option C. heat of combustion.
Correct Answer is. heat of combustion.
Explanation. The energy content of fuel is known as 'heat of combustion'.

Question Number. 32. The transfer of heat through radiation is achieved by the application of radioactive isotopes.
Option A. the application of radioactive isotopes.
Option B. warming up the intervening medium.
Option C. not warming up the intervening medium.
Correct Answer is. warming up the intervening medium.
Explanation. NIL.

Question Number. 33. The dew point is.
Option A. the point when air is cooled at which the moisture just starts to condense.
Option B. the point at which air can be heated.
Option C. the point when air is cooled at which the moisture does not condense.
Correct Answer is. the point when air is cooled at which the moisture just starts to condense.
Explanation. Check the definition of dew point.

Question Number. 34. What are common refrigerant agents?.
Option A. formaldehyde, ammonia, carbon dioxide.
Option B. water, freon, ammonia.
Option C. Dry ice, methyl bromide, water.
Correct Answer is. water, freon, ammonia.
Explanation. Water is used in cooling towers (and when you sweat). Freon and ammonia are commonly used in fridges and air-con systems.

Question Number. 35. During a process of gas heating, no heat is absorbed or given out. It is.
Option B. isochoric.
Option C. isothermal.
Explanation. No heat absorbed or given out is 'adiabatic'.

Question Number. 36. During a pressurising process, all heat is given away. It is.
Option B. isochoric.
Option C. isothermal.
Explanation. All heat given away keeps the process at constant temperature - thus 'isothermal'.

Question Number. 37. A material capable of going direct from solid to gas is a.
Option A. substrate.
Option B. substance.
Option C. sublimate.
Explanation. A sublimate can go directly from solid to gas.

Question Number. 38. The composition of the atmosphere is approximately.
Option A. 1/5 oxygen and 4/5 nitrogen.
Option B. 4/5 oxygen and 1/5 nitrogen.
Option C. 2/5 oxygen and 3/5 nitrogen.
Correct Answer is. 1/5 oxygen and 4/5 nitrogen.
Explanation. Air is 78% (approx. 4/5) nitrogen and 21% (approx 1/5) oxygen.

Question Number. 39. What is meant by adiabatic?.
Option A. All heat crosses the boundary.
Option B. No heat crosses the boundary.
Option C. Some heat crosses the boundary.
Correct Answer is. No heat crosses the boundary.
Explanation. No heat is lost or gained in an adiabatic process.

Question Number. 40. If a gas is heated and its temperature is raised by 1K. What happens to its volume?.
Option A. Decreases by 1/273.
Option B. Increases by 1/273.
Option C. Remains the same.
Correct Answer is. Increases by 1/273.
Explanation. Charles's Law. Also how the absolute zero (-273 °C is calculated).

Question Number. 41. If a block of ice melts in a glass of water, the level of water in the glass will.
Option A. fall.
Option B. rise.
Option C. remain the same.
Correct Answer is. remain the same.
Explanation. NIL.

Question Number. 42. If heat is constant, and if pressure increases on a liquid what will the volume do?.
Option A. Increase.
Option B. Remains constant.
Option C. Decrease.
Explanation. Liquids are considered incompressible, therefore their volume remains constant.

Question Number. 43. Radiant heat of a body, heated from a radiant source is.
Option A. inversely proportional to the square of the distance.
Option B. proportional to distance.
Option C. inversely proportional.
Correct Answer is. inversely proportional to the square of the distance.
Explanation. The wording of this question is terrible, but it is probably referring to radiant heat being inversely proportional to the square of the distance from the source of the.

Question Number. 44. Combined gas law relates volume, pressure and.
Option A. temperature.
Option B. density.
Option C. velocity.
Explanation. P1V1/T1 = P2V2/T2 Combined (or ideal) gas law.

Question Number. 45. The heat given off by burning a 1kg block of wood is.
Option A. transmissive heat.
Option C. latent heat.
Explanation. The embers of burning wood produce radiant heat.

Question Number. 46. H20 in what form holds most energy?.
Option A. Steam.
Option B. Ice.
Option C. Water.
Explanation. Water in the form of steam has the most energy.

Question Number. 47. A block of metal is melted. It will.
Option A. remain the same volume.
Option B. decrease in volume.
Option C. increase in volume.
Correct Answer is. increase in volume.
Explanation. NIL.

Question Number. 48. The energy that ice at 0 °C must gain so that it turns to water at 0 °C is called.
Option A. the latent heat of vaporisation.
Option B. sensible energy.
Option C. the latent heat of fusion.
Correct Answer is. the latent heat of fusion.
Explanation. Fusion means 'to melt'.

Question Number. 49. Ideal gas goes through an isothermal process. It is in accordance with which law?.
Option A. Gay Lussac's.
Option B. Boyle's.
Option C. Charles's.
Explanation. Boyle's Law (P/V = constant) assumes constant temperature (isothermal).

Question Number. 50. The Steam Point of water is.
Option A. 0 Kelvin.
Option B. 373 Kelvin.
Option C. 273 Kelvin.
Explanation. K = C + 273.

Question Number. 51. A 200 cm titanium bar increases in length by 2 cm when its temperature rises by 100 °C. Its linear expansivity is.
Option A. 0.0101 per °C.
Option B. 0.01 per °C.
Option C. 0.0001 per °C.
Correct Answer is. 0.0001 per °C.
Explanation. Expansion = L x alpha x temp.change So alpha = Expansion/(L x temp.change) = 2/(200 * 100) = 0.0001 per °C.

Question Number. 52. Heat transmission by convection is confined to.
Option A. liquids and gases.
Option B. gases and solids.
Option C. solids and liquids.
Correct Answer is. liquids and gases.
Explanation. In convection, the material must 'flow' and carry the heat with it.

Question Number. 53. Which contains the least amount of heat energy?.
Option A. Both 1 kg of ice at 0 °C and 1 kg of water at 0 °C have the same amount of heat energy.
Option B. 1 kg of water at 0 °C.
Option C. 1 kg of ice at 0 °C.
Correct Answer is. Both 1 kg of ice at 0 °C and 1 kg of water at 0 °C have the same amount of heat energy.
Explanation. The temperature only is a measure of the heat energy, not the state.

Question Number. 54. Which weighs the most?.
Option A. 1 kg of ice at 0 °C.
Option B. Both 1 kg of ice at 0 °C and 1 kg of water at 0 °C have the same weight.
Option C. 1 kg of water at 0 °C.
Correct Answer is. Both 1 kg of ice at 0 °C and 1 kg of water at 0 °C have the same weight.
Explanation. NIL.

Question Number. 55. Which has the greatest density?.
Option A. 1 kg of ice at 0 °C.
Option B. 1 kg of water at 0 °C.
Option C. Both 1 kg of ice at 0 °C and 1 kg of ice at 0 °C have the same density.
Correct Answer is. Both 1 kg of ice at 0 °C and 1 kg of ice at 0 °C have the same density.
Explanation. NIL.

Question Number. 56. Which has the greatest volume?.
Option A. 1 kg of water at 0 °C.
Option B. 1 kg of ice at 0 °C.
Option C. Both 1 kg of ice at 0 °C and 1 kg of ice at 0 °C have the same volume.
Correct Answer is. Both 1 kg of ice at 0 °C and 1 kg of ice at 0 °C have the same volume.
Explanation. NIL.

Question Number. 57. The temperature at which water will exist as a solid, liquid and gas, all at the same time, is called.
Option A. the triple point and is approximately 0 °C.
Option B. the tri-state point and is approximately at 0 °C.
Option C. the tri-state point and is approximately 98 °C.
Correct Answer is. the triple point and is approximately 0 °C.
Explanation. NIL.

Question Number. 58. Material A and material B are both removed from the same oven at the same time, after being in the same amount of time. Material A is a higher temperature than material B. This is because.
Option A. material B has a higher specific heat capacity.
Option B. material A must have had a higher temperature before it was put in the oven.
Option C. material A has a higher specific heat capacity.
Correct Answer is. material A has a higher specific heat capacity.
Explanation. NIL.

4. Optics (Light).

Question Number. 1. What is the thickness of a single mode fibre optic?.
Option A. 200 micrometres.
Option B. 5 micrometres.
Option C. 50 micrometres.
Explanation. Introduction to Fiber Optics 3rd Edition John Crisp and Barry Elliot Page 67.

Question Number. 2. Divergent light rays give rise to.
Option A. a real image.
Option B. a virtual image.
Option C. chromatic aberrations.
Correct Answer is. a virtual image.
Explanation. NIL.

Question Number. 3. In fibreoptics the type of cable is chosen by.
Option A. matching the diameter of the cable to the wavelength.
Option B. distance required to travel.
Option C. the strength of signal needed.
Correct Answer is. distance required to travel.
Explanation. Introduction to Fiber Optics by John Crisp.

Question Number. 4. A material with a gradually varying refractive index is said to have a.
Option B. step index.
Option C. single index.
Explanation. Introduction to Fiber Optics by John Crisp.

Question Number. 5. Fibre optic cables are capable of transmitting light at.
Option A. 1.99 * 108 m/s.
Option B. 3 * 108 m/s.
Option C. 0.99 * 108 m/s.
Correct Answer is. 1.99 * 108 m/s.
Explanation. Speed of light in a vacuum is 3 * 10 to the power 8. But the refractiv index of glass is about 1.5. So divide 3 * 10 to the power 8 by 1.5...Introduction to Fiber Optics by John Crisp.

Question Number. 6. Step index fibres suffer from.
Option A. dispersion.
Option B. scatter.
Option C. attenuation.
Explanation. Dispersion also limits the bandwidth in step index fibres. Introduction to Fiber Optics by John Crisp.

Question Number. 7. Attenuated pulses have their sizes and shape restored by.
Option A. regenerators.
Option B. impedance matching transformers.
Option C. opto-isolators.
Explanation. Regenerators are placed in the fibre optic line (usually not less than 1 km spacings) to boost the signal (like a relay system). Thus reducing attenuation at the recieving end. Introduction to Fiber Optics by John Crisp.

Question Number. 8. Attenuation in fibre optic cables is most often caused by.
Option A. backscattering and microbends.
Option B. microbends and scattering.
Option C. absorption and scattering.
Correct Answer is. absorption and scattering.
Explanation. Although all three (microbends, scattering and absorbtion) cause attenuation in fibre optics, microbends are the most easy to manufacture out of the cable. Introduction to Fiber Optics by John Crisp.

Question Number. 9. For a concave lens the image is.
Option A. virtual.
Option B. real.
Option C. a chromatic orb.
Explanation. NIL.

Question Number. 10. In a fibre optic flying control system.
Option A. the sensor and the transmitter require electrical power.
Option B. the transmitter requires power.
Option C. the sensor requires electrical power.
Correct Answer is. the sensor and the transmitter require electrical power.
Explanation. The transmitter is an LED or laser (both need power) and the receiver is a photodiode, which needs electrical power. Introduction to Fiber Optics by John Crisp.

Question Number. 11. Photons in a semiconductor are stimulated to produce excess photons to be emitted. This is a.
Option A. photodiode.
Option B. laser diode.
Option C. LED.
Explanation. LASER - Light Amplification by the Stimulated Emition of Radiation. Introduction to Fiber Optics by John Crisp.

Question Number. 12. In a fibre optic flying control system, which of the following are used?.
Option A. Single mode fibre.
Option B. Multi mode fibre.
Option C. Dual mode fibre.
Correct Answer is. Multi mode fibre.
Explanation. Introduction to Fiber Optics by John Crisp.

Question Number. 13. A fibre optic cable is attenuated at 29 dB/metre. This is referring to.
Option A. allowable loss.
Option B. the figure allowed for when calculating power gain.
Option C. the maximum cable run allowed in the system.
Correct Answer is. the figure allowed for when calculating power gain.
Explanation. Introduction to Fiber Optics by John Crisp.

Question Number. 14. The fibre optic receiver is a.
Option A. laser diode.
Option B. photodiode.
Option C. light emitting diode.
Explanation. Introduction to Fiber Optics by John Crisp.

Question Number. 15. Regenerators are used in fibre optic systems to reduce.
Option A. dispersion.
Option B. random emission.
Option C. attenuation.
Explanation. Introduction to Fiber Optics by John Crisp.

Question Number. 16. When light rays enter a medium with a different refractive index they.
Option A. change direction.
Option B. reflect.
Option C. change speed.
Explanation. They will only change direction if they hit the surface at an angle other than 0 degrees (to the normal). It will always change speed however.

Question Number. 17. A converging lens can focus light rays because.
Option A. the incoming rays are already converging.
Option B. it is spherical.
Option C. the light rays travel more slowly at the centre.
Correct Answer is. it is spherical.
Explanation. A converging lens is a part of a sphere, so light rays hit it at different angles depending upon its distance from the principle axis.

Question Number. 18. If a ray of light enters a fibre optic cable with a refractive index of 1.5, what is the speed of the ray in the cable?.
Option A. 300,000 kilometres per second.
Option B. 400,000 kilometres per second.
Option C. 200,000 kilometres per second.
Correct Answer is. 200,000 kilometres per second.
Explanation. vacuum / speed of light in medium. 1.5 = 300,000 / C, C = 200,000 km/s. Introduction to Fiber Optics by John Crisp.

Question Number. 19. vacuum / speed of light in medium. 1.5 = 300,000 / C, C = 200,000 km/s. Introduction to Fiber Optics by John Crisp.
Option A. a constant refractive index across its cross sectional area.
Option B. a variable refractive index across its cross sectional area.
Option C. a sudden change in refractive index.
Correct Answer is. a variable refractive index across its cross sectional area.
Explanation. Introduction to Fiber Optics by John Crisp.

Question Number. 20. A mirror.
Option A. refracts all light.
Option B. reflects all light.
Option C. absorbs a percentage of light.
Correct Answer is. absorbs a percentage of light.
Explanation. NIL.

Question Number. 21. The width of a multimode fibre optic cable (including the cladding) is.
Option A. 1 µm.
Option B. 100 µm.
Option C. 10 µm.
Explanation. This must be referring to the 'overall' diameter - i.e that of the cladding, since the core is 50 or 62.5 micrometers (microns). Introduction to Fiber Optics by John Crisp.

Question Number. 22. A varying refractive index optical fibre is a.
Option A. single index.
Option C. step index.
Explanation. Introduction to Fiber Optics by John Crisp.

Question Number. 23. Refractive index is.
Option A. the speed of light in the medium divided by the speed of light in air.
Option B. the speed of light in air divided by the speed of light in the medium.
Option C. the speed of light in air multiplied by the speed of light in the medium.
Correct Answer is. the speed of light in air multiplied by the speed of light in the medium.
Explanation. Introduction to Fiber Optics by John Crisp page 11.

Question Number. 24. What is the speed of light in km/s?.
Option A. 3000.
Option B. 3 * 108.
Option C. 300000.
Explanation. 300,000,000 m/s = 300,000,000/1000 km/s = 300,000 km/s. Introduction to Fiber Optics by John Crisp.

Question Number. 25. The focal point of a mirror is.
Option C. 2 * the radius.
Explanation. NIL.

Question Number. 26. What is the speed of light in air at 0 °C.
Option A. 331 m/s.
Option B. 300 m/µs.
Option C. 331 mm/s.
Explanation. Standard figure is 300,000,000 m/s. Convert that to m/microsecond and you must divide by 1,000,000. Introduction to Fiber Optics by John Crisp.

Question Number. 27. How far will light travel in one year?.
Option A. 9.46 * 1015 m.
Option B. 1.5 * 1011 m.
Option C. 3 * 1015 m.
Correct Answer is. 9.46 * 1015 m.
Explanation. 60 * 60 * 24 * 365 * 300000000 = 9.46.... What a calculation to do without your calculator - estimate as best you can.

Question Number. 28. When different signals are transmitted down a fibre optic core, are they distinguished by a.
Option A. active filter.
Option B. passive filter.
Option C. star coupler.
Explanation. A 'passive filter' simply sorts out and/or blocks certain wavelengths. An 'active filter' will catch certain wavelengths and convert them to other wavelength. Introduction to Fiber Optics by John Crisp.

Question Number. 29. On an Optical Time Domain Reflectometer (OTDR), the amount of attenuation in the cable is.
Option A. read from the cathode ray display.
Option B. derived from a graph.
Option C. dialed into OTDR.
Explanation. See 'Introduction to Fiber Optics' pg. 157. Introduction to Fiber Optics by John Crisp.

Question Number. 30. In a flat surfaced mirror, the angle of reflection is.
Option A. equal to the angle of incidence.
Option B. less than the angle of incidence.
Option C. more than the angle of incidence.
Correct Answer is. equal to the angle of incidence.
Explanation. The angle of incidence is the angle the light makes with the 'normal' line. The angle of reflection is equal on the other side of the 'normal' line.

Question Number. 31. In a multimode fibre optic cable, the.
Option A. diameter is greater than the wavelength.
Option B. diameter is less than the wavelength.
Option C. diameter is equal to the wavelength.
Correct Answer is. diameter is greater than the wavelength.
Explanation. Multimode fibres are bigger than single mode fibres. Introduction to Fiber Optics by John Crisp.

Question Number. 32. A converging lens converges light rays because.
Option A. it is not a sphere.
Option B. the light source is already converging.
Option C. the light waves are refracted less in the centre of the lens than they are at the extremities.
Correct Answer is. the light waves are refracted less in the centre of the lens than they are at the extremities.
Explanation. NIL.

Question Number. 33. In fibre optics. The fibre cable has a refractive index of 1.5, what is its speed?.
Option A. 300 meters/microsecond.
Option B. 400 meters/microsecond.
Option C. 200 meters/microsecond.
Explanation. n = speed of light in vacuum / speed of light in substance. 1.5 = 300m per microsecond / speed of light in fibre. Transpose.. Introduction to Fiber Optics by John Crisp.

Question Number. 34. A material, which has a varying refractive index is a.
Option A. step index.
Option B. single index.
Option C. double index.
Explanation. A varying refractive index is either 'step index' or 'graded index'. Step index is the only answer available. Introduction to Fiber Optics by John Crisp.

Question Number. 35. A ray of light that travels through the centre of curvature of a concave mirror before being reflected, how is it reflected?.
Option A. Through the focal point.
Option B. Neither of the above.
Option C. Through the centre of curvature.
Correct Answer is. Through the focal point.
Explanation. The focal point and the centre of curvature of the concave mirror lie on the same center line. A ray of light travelling along that centre line will be reflected right back along the same path - through the focal point.

Question Number. 36. What will the image produced through a divergent lens be?.
Option A. Negative.
Option B. Real.
Option C. Virtual.
Explanation. The image produced by a divergent (concave) lens is a 'VIRTUAL' image. i.e you could not take a photograph of it.

Question Number. 37. When a beam of light passes from one medium to another with a different refractive index, what will happen to the beam of light?.
Option A. Total internal reflection.
Option B. Change speed.
Option C. Total internal refraction.
Explanation. A beam of light passes from one medium to another - its speed will change. This is the only statement of certainty, since no information is given about the angle of incidence.

Question Number. 38. A fibre optic cable has different refractive indexes across its core diameter, it is a.
Option A. single mode fibre.
Option C. step index fibre.
Explanation. A fibre optic with a different refractive index across its core diameter is a 'graded index'. Introduction to Fiber Optics by John Crisp.

Question Number. 39. Incident light travelling from air to water, the light is.
Option A. bent towards the normal.
Option B. not bent.
Option C. bent away from the normal.
Correct Answer is. bent towards the normal.
Explanation. Light travelling from air to water, the waves are bent (or angled) less when measured to the normal.

Question Number. 40. If a light is beamed at a flat mirror, what is the angle it reflects at?.
Option A. Reflective index.
Option B. Angle of incidence.
Option C. Reactive angle.
Correct Answer is. Angle of incidence.
Explanation. The angle the light hits a mirror (to the normal) is the Angle of Incidence. The angle it bounces off (to the normal) is the Angle of Reflection. The two angles are always equal.

Question Number. 41. In a graded index multimode fibre is the refractive index.
Option A. is high.
Option B. varies high and low.
Option C. is low.
Correct Answer is. varies high and low.
Explanation. In a graded index fibre optic cable, the refractive index is low at the edge, high in the centre and then low at the other edge. Introduction to Fiber Optics by John Crisp.

Question Number. 42. The fibre optic receiver is a.
Option A. photodiode.
Option B. laser diode.
Option C. light emitting diode.
Explanation. The fibre optic receiver is a photo diode. Introduction to Fiber Optics by John Crisp.

Question Number. 43. The usable bandwidth of a fibre is determined by.
Option A. the wavelength of the light.
Option B. the angle of total internal reflection.
Option C. the intermodal dispersion.
Correct Answer is. the intermodal dispersion.
Explanation. Bandwidth is the range of frequencies that can be transmitted. Since different frequencies travel at different speed (in glass) they will arrive at the other end at different times. This is the cause of intermodal dispersion. Introduction to Fiber Optics by John Crisp.

Question Number. 44. If, with a concave mirror the image is placed beyond the centre of curvature, the image produced will be.
Option A. virtual, erect and larger.
Option B. real, inverted and smaller.
Option C. real, erect and larger.
Correct Answer is. real, inverted and smaller.
Explanation.

Question Number. 45. The power of a lens is calculated from the.
Option A. reciprocal of the focal length.
Option B. product of the focal length and its distance from the pole.
Option C. focal length squared.
Correct Answer is. reciprocal of the focal length.
Explanation. focal length squared.

Question Number. 46. Single mode optical fibre cable will.
Option A. have several light rays to pass.
Option B. have diameter matched to wavelength of light passed.
Option C. cause distortion to the light wave at the output end which is dependent upon the length of the cable.
Correct Answer is. have diameter matched to wavelength of light passed.
Explanation. Introduction to Fiber Optics John Crisp page 64.

Question Number. 47. When an emergent light wave enters a divergent lens.
Option A. it will focus beyond the lens.
Option B. it will focus behind the lens.
Option C. it is s spherical.
Correct Answer is. it will focus behind the lens.
Explanation. A divergent lens (also known as concave lens) focuses the image on the same side of the lens as the object. It is therefore a virtual image.

Question Number. 48. In a concave mirror, light rays parallel to mirror axis will be reflected.
Option A. through the focal point.
Option B. back to the centre of curvature.
Option C. parallel to mirror axis.
Correct Answer is. through the focal point.
Explanation. All the light rays focus at the focal point.

Question Number. 49. In a concave mirror, a light ray passing through the focal point will be reflected.
Option A. through the focal point.
Option B. on the centre line of the mirror.
Option C. parallel to the axis.
Correct Answer is. parallel to the axis.
Explanation. All rays which pass through the focal point, reflect from the mirror then travel parallel to the axis.

Question Number. 50. A passive sensor.
Option A. does not require power.
Option B. requires power for the sensor.
Option C. requires power for the transmitter.
Correct Answer is. does not require power.
Explanation. Passive sensors do not require power. Introduction to Fiber Optics by John Crisp.

Question Number. 51. Refractive index is.
Option A. lower for 4ºC water than 0ºC ice.
Option B. higher for diamond than acrylic.
Option C. highest for water.
Correct Answer is. higher for diamond than acrylic.
Explanation. Diamond has the highest refractive index. Note: 4 °C. water is more dense than ice so has greater refractive index.

Question Number. 52. For optical fibres, the refractive index of the cladding compared to that of the core.
Option A. can be either bigger or smaller depending on specification.
Option B. is always smaller.
Option C. is always larger.
Correct Answer is. is always smaller.
Explanation. Cladding always has a lower refractive index. Introduction to Fiber Optics by John Crisp.

Question Number. 53. The ability for a fibreoptic cable to carry waves is dependent on.
Option A. material, absorption and speed of light.
Option B. internal reflection.
Option C. material, diameter and absorption.
Explanation. Fiber optics carry light by Total Internal Reflection. Introduction to Fiber Optics by John Crisp.

Question Number. 54. In spherical aberrations.
Option A. incident rays further from the axis intersect slightly closer to the lens to produce a distorted picture.
Option B. incident rays further from the axis intersect slightly further away from the lens to produce a distorted picture.
Option C. the bending of light through lens intersect at the same point (achromatic lens).
Correct Answer is. incident rays further from the axis intersect slightly closer to the lens to produce a distorted picture.
Explanation. NIL.

Question Number. 55. In a fibre optic flying control system.
Option A. the sensor and transmitter require electrical power.
Option B. the sensor inputs to the transmitter which needs electrical power.
Option C. the sensor needs electrical power.
Correct Answer is. the sensor and transmitter require electrical power.
Explanation. The sensor is a photodiode or a PIN diode (needs power) and the transmitter is an LED or laser (needs power). Introduction to Fiber Optics by John Crisp.

Question Number. 56. In fibreoptics, the type of cable is chosen by.
Option A. the strength of signal needed.
Option B. matching the diameter of the cable with the wavelength.
Option C. distance required to travel.
Correct Answer is. distance required to travel.
Explanation. Type of cable (not the diameter) - single mode, multimode or graded index etc. is chosen for its attenuation and hence length. Introduction to Fiber Optics by John.

Question Number. 57. When refraction takes place.
Option A. the frequency remains constant.
Option B. the speed of the wave remains constant.
Option C. the wavelength remains constant.
Correct Answer is. the frequency remains constant.
Explanation. Frequency remains constant.

Question Number. 58. When light meets a Glass / Air boundary at an angle of incidence less than the critical angle.
Option A. Total Internal Reflection takes place.
Option B. no light is reflected.
Option C. both reflection and refraction takes place.
Correct Answer is. both reflection and refraction takes place.
Explanation. Even at angles less than the critical, a small portion of the light in reflected Introduction to Fiber Optics by John Crisp.

Question Number. 59. An object placed more than twice the focal length beyond a converging lens will form an image that is.
Option A. inverted, larger and virtual.
Option B. inverted, smaller and real.
Option C. erect, smaller and real.
Correct Answer is. inverted, smaller and real.
Explanation. NIL.

Question Number. 60. A parabolic mirror may be used to prevent.
Option A. lateral inversion.
Option B. spherical aberration.
Option C. formation of a penumbra.
Explanation. NIL.

Question Number. 61. The refractive index for air is approximately.
Option A. 1.
Option B. 10.
Option C. 0.
Explanation. Introduction to Fiber Optics by John Crisp.

Question Number. 62. In optical fibres the total internal reflection of light only occurs at angles.
Option A. less than the critical angle.
Option B. equal to the critical angle.
Option C. greater than the critical angle.
Correct Answer is. greater than the critical angle.
Explanation. Remember that the critical angle is measured from the normal (or perpendicular) to the surface. Introduction to Fiber Optics by John Crisp page 15.

Question Number. 63. In a concave mirror, if an object is placed between the focal point and the pole, the image will be.
Option A. real, erect and diminished.
Option B. virtual and on the opposite side.
Option C. real, inverted and larger.
Correct Answer is. virtual and on the opposite side.
Explanation. NIL.

Question Number. 64. The purpose of a patch cord used with an OTDR is.
Option A. to compensate for any contraction of the Fiber optic cable during test.
Option B. to overcome the dead zone problem caused by reflection at OTDR launch connector.
Option C. to attenuate OTDR output power which could cause damage to the cable under test.
Correct Answer is. to overcome the dead zone problem caused by reflection at OTDR launch connector.
Explanation. Introduction to Fiber Optics John Crisp Page 156.

Question Number. 65. The power of a lens is measured in.
Option A. Lumens per Watt.
Option B. Watts.
Option C. Diopters.
Explanation. NIL.

Question Number. 66. For a concave lens, the image is.
Option A. real.
Option B. virtual.
Option C. a chromatic orb.
Explanation. NIL.

Question Number. 67. Lasers use which source of light?.
Option A. Scattered.
Option B. Refraction.
Option C. Coherent.
Explanation. Introduction to Fiber Optics by John Crisp.

Question Number. 68. Illumination of one lumen per metre squared is one.
Option A. luxor.
Option B. lux.
Option C. candle.
Explanation. NIL.

Question Number. 69. The amount of light emitted by a lamp can be measured in.
Option A. candle's.
Option B. luxors.
Option C. lumens.
Explanation. NIL.

Question Number. 70. The light gathering power of a lens is indicated by its.
Option A. material.
Option B. thickness of the lens.
Option C. focal ratio.
Explanation. NIL.

Question Number. 71. In order for a converging lens to form a real image, the object distance must be more than.
Option A. focal length.
Option B. 5 times the thickness of the lens.
Option C. 1 inch.
Explanation. NIL.

Question Number. 72. A ______ lens is thicker in the middle than at the edges. It is.
Option A. converging.
Option B. concave.
Option C. upsharp.
Explanation. NIL. http://www.phys.hawaii.edu/~teb/optics/java/clens/

Question Number. 73. When is the only time a concave mirror forms a virtual image?.
Option A. When the object is at the focal point.
Option B. When the object is inside the focal point.
Option C. When the object is placed at the centre of curvature.
Correct Answer is. When the object is inside the focal point.
Explanation. NIL. http://www.glenbrook.k12.il.us/gbssci/phys/class/refln/u13l3e.html

Question Number. 74. A convex mirror forms a virtual image when.
Option A. the object is at the centre of curvature.
Option B. the object is inside the focus.
Option C. always.
Explanation. NIL.

Question Number. 75. A Concave mirror is used in.
Option A. a rear view mirror.
Option B. a periscope.
Explanation. NIL.

5. Wave Motion and Sound.

Question Number. 1. When the movement of an object rotating around a radius at a constant speed is projected onto a plane, the projected image follows what path?.
Option A. Sinusoidal.
Option B. Lateral.
Option C. Longitudinal.
Explanation. NIL.

Question Number. 2. The speed of sound in air at 0 °C is approximately.
Option A. 331 m/s.
Option B. 3 * 108 m/s.
Option C. 181 m/s.
Explanation. NIL.

Question Number. 3. If a wave traveling to a point meets a wave traveling from that point, of equal frequency.
Option A. the two waves cancel each other out.
Option B. they will have no effect on each other.
Option C. a standing wave is formed.
Correct Answer is. a standing wave is formed.
Explanation. NIL.

Question Number. 4. Quality of sound depends upon.
Option A. pure sound waves being produced by the source.
Option B. frequency and harmonics of the waves being produced.
Option C. quality of the receiver.
Correct Answer is. frequency and harmonics of the waves being produced.
Explanation. NIL.

Question Number. 5. Particles vibrating in air.
Option A. tend to give off heat.
Option B. tend to give off light.
Option C. produce waves.
Explanation. Particles vibrating in air produce sound.

Question Number. 6. The fundamental frequency is the.
Option A. 3rd harmonic.
Option B. 1st harmonic.
Option C. 2nd harmonic.
Explanation. NIL.

Question Number. 7. The first overtone of a sound wave is the.
Option A. 1st harmonic.
Option B. fundamental frequency.
Option C. 2nd harmonic.
Explanation. NIL.

Question Number. 8. Two pure tones of similar frequency are heard by a person. What will they hear?.
Option A. One pure tone.
Option B. A beat of the two tones.
Option C. Two tones.
Correct Answer is. A beat of the two tones.
Explanation. At certain points, the troughs cancel the peaks. At other points the peaks 'add to' other peaks. The net effect is a low frequency oscillation in amplitude.".

Question Number. 9. Two sound waves of the same frequency and amplitude are moving half a wavelength out of phase with each other. What will be heard?.
Option A. Nothing.
Option B. Twice the volume of one of the sound waves.
Option C. Half the volume of one of the sound waves.
Explanation. The peaks will cancel the troughs.

Question Number. 10. A fire engine is approaching you with its siren on. As it passes you its pitch.
Option A. stay the same.
Option B. increases.
Option C. decreases.
Explanation. NIL.

Question Number. 11. Quality of sound is dependant on.
Option A. number and pitch of harmonics.
Option B. medium it is traveling through.
Option C. frequency of the supply.
Correct Answer is. number and pitch of harmonics.
Explanation. Quality of sound is dependant upon the number of harmonics and the pitch.

Question Number. 12. What frequency is a tone which is 4 times the fundamental frequency?.
Option A. 2nd overtone.
Option B. 3rd overtone.
Option C. 3rd harmonic.
Explanation. The 4th harmonic is also called the 3rd overtone.

Question Number. 13. Intensity of sound waves.
Option A. is not affected by distance.
Option B. varies inversely as the square of distance from source.
Option C. vary directly as per distance from source.
Correct Answer is. varies inversely as the square of distance from source.
Explanation. Sound diminishes with the square of the distance from the source (i.e double the distance = 1/4 the dB, triple the distance = 1/9 the dB etc.) - Technically called a log-linear scale.

Question Number. 14. In a standing wave the point where continuous vibration of maximum amplitude occurs is called the.
Option A. harmonic.
Option B. anti-node.
Option C. node.
Explanation. The peaks are the anti-nodes. See External website.

Question Number. 15. The name given to sounds below that which the human ear can detect, i.e. below 20Hz is.
Option A. ultra sound.
Option B. infra sound.
Option C. sonic pitch.
Explanation. See how silent thunder can shatter windows at External website.

Question Number. 16. The speed of sound in dry air is 331 m/s. In a solid the speed would.
Option A. increase.
Option B. decrease.
Option C. stay the same.
Explanation. Speed of sound is greater in a solid than in air.

Question Number. 17. If a tuning fork is struck and held close to the ear and slowly rotated about the vertical axis, in one rotation how many times is there no sound?.
Option A. 2.
Option B. Sound is audible for the whole revolution.
Option C. 4.
Explanation. Two sound waves interfere creating a relatively 'dead' zone for approximately 2 quarters of the rotation.

Question Number. 18. What is the phenomenon that occurs when a siren that approaches you, at the point of passing, the pitch decreases?.
Option A. Resonance.
Option B. Doppler effect.
Option C. Echo.
Explanation. Doppler effect.

Question Number. 19. For hearing protection, noise cancelling headphones.
Option A. cannot reduce the noise from outside completely.
Option B. operate by destructive interference of sound waves.
Option C. operate by constructive interference of sound waves.
Correct Answer is. operate by destructive interference of sound waves.
Explanation. NIL.

Question Number. 20. Tuning forks are used to vibrate musical instruments because.
Option A. they produce both of the other effects described.
Option B. they produce a beat when played together with the instrument.
Option C. they produce a pure note.
Correct Answer is. they produce a pure note.
Explanation. A tuning fork produces a pure note, which can be used to tune a guitar (for example) by listening for the beat produced when played alongside an out-of-tune string.

Question Number. 21. When an open pipe is played and a note is heard.
Option A. the lowest frequency of the note is called second harmonic.
Option B. resonance occurs with standing waves set up inside the pipe.
Option C. there is a 180º phase change at the open end.
Correct Answer is. resonance occurs with standing waves set up inside the pipe.
Explanation. NIL.

Question Number. 22. Two sound waves are the same but slightly out of phase. This means that.
Option A. the beat frequency is the same.
Option B. there will be no beat frequency.
Option C. the beat frequency will be slightly different.
Correct Answer is. the beat frequency is the same.
Explanation. The beat frequency is the same frequency as either of the two frequencies.

Question Number. 23. In a vibrating string, the point at which there is no displacement is called a.
Option A. antinode.
Option B. node.
Option C. fundamental mode.
Explanation. NIL.

Question Number. 24. The amplitude of a Transverse Wave is the distance from.
Option A. the top of a peak to the bottom of a trough.
Option B. half the distance from peak to trough.
Option C. one peak to the next.
Correct Answer is. half the distance from peak to trough.
Explanation. NIL.

Question Number. 25. Increasing the Amplitude of a sound wave increases its.
Option A. pitch.
Option B. moment.
Option C. loudness.