# Illumination Engineering mcq pdf | Electrical Engineering

Below are the 70 most important illumination engineering mcq questions with answers. We are also planning to provide Illumination engineering mcq pdf downloading link along with IE mcq. These Illumination Engineering (IE) multiple choice questions are for online exams and interviews.

## Illumination Engineering mcq

Q. 1. Radiant efficiency of the luminous source depends on
A : shape of the source
B : temperature of the source
C : wavelength of light rays
D : all of the above.

temperature of the source

Q. 2. Light waves travel with a velocity of
A : 3 x 1010cm/s
B : 3 x 1012cm/s
C : 3 x 1015 cm/s
D : 3 x 1018 cm/s

3 x 10^10cm/s

Q. 3. Carbon arc lamps are commonly used in
A : domestic lighting
B : street lighting
C : cinema projectors
D : photography.

cinema projectors

Q. 4. The unit of solid angle is
A : solid angle
D : candela.

Q. 5. Candela is the unit of
A : Luminous flux
B : Luminous intensity
C : Wavelength
D : None of the above.

Luminous intensity

Q. 6. The unit of luminous flux is
B : candela
C : lumen
D : lux.

lumen

Q. 7. The illumination is directly proportional to the cosine of the angle made by the normal to the illuminated surface with the direction of the incident flux. Above statement is associated with
A : Planck’s law
B : Macbeth’s law of illumination
C : Bunsen’s law of illumination
D : Lambert’s cosine law.

Lambert’s cosine law.

Q. 8. Illumination level required for precision work is around
A : 50 lm/m2
B : 100 lm/m2
C : 200 lm/m2
D : 500 lm/m2

500 lm/m2

Q. 9. Which of the following will need the highest level of illumination ?
B : Bed rooms
C : Hospital wards
D : Railway platforms.

Q. 10. Which of the following will need lowest level of illumination ?
A : Displays
B : Fine engraving
C : Railway platform
D : Auditoriums.

Railway platform

Q. 11. Which of the following lamp gives nearly monochromatic light ?
A : Sodium vapor lamp
B : GLS lamp
C : Tube light
D : Mercury vapor lamp.

Sodium vapor lamp

Q. 12. The illumination level in houses is in the range
A : 10-20 lumen/m2
B : 30 – 50 lumen/m2
C : 40-75 lumen/m2
D : 100-140 lumen/m2

100-140 lumen/m2

Q. 13. Luminous efficiency of a fluorescent tube is
A : 5- 10 lumens/watt
B : 15-20 lumens/watt
C : 30 – 40 lumens/watt
D : 60 – 65 lumens/watt.

60 – 65 lumens/watt.

Q. 14. One lumen per square meter is the same as
A : One lux
B : One candela
C : One foot candle
D : One lumen meter.

One lux

Q. 15. Standard wattage of 3 ft. fluorescent tube is
A : 10 W
B : 40 W
C : 65 W
D : 100 W.

40 W

Q. 16. For the same wastage which lamp is cheapest ?
A : Sodium vapor lamp
B : Mercury vapor lamp
C : Fluorescent tube
D : GLS lamps.

GLS lamps.

Q. 17. Optical instruments used for the comparison of candle powers of different sources arc known as
A : Candle meters
C : Bunsen meter
D : Photo meter.

Photo meter.

Q. 18. Which photometer is used for comparing the lights of different colors ?
A : Bunson photometer
B : Grease spot photometer
C : Lummer Brodhum photometer
D : Guilds Flicker Photometer

Guilds Flicker Photometer

Q. 19. Which photometer depends for its operation on Lambert’s cosine law ?
A : Macbeth lllumino meter
B : Trotter Illumination Photometer
C : Lummer Brodhum Photometer
C : Guild’s Flicker Photometer.

Trotter Illumination Photometer

Q. 20. Which photometer depends for its operation on Inverse Square Law ?
A : Guilds Flicker Photometer
B : Lummer Brodhum Photometer
C : Macbeth llluminometer
D : Trotter Illumination Photometer.

Macbeth llluminometer

Q. 21. The color temperature of day light is around
A : 50 K
B : 160 K
C : 600 K
D : 6000 K.

6000 K.

Q. 22. Light is produced in electric discharge lamps by
A : heating effect of current
B : magnetic effect of current
C : ionization in a gas or vapor
D : carbon electrodes.

ionization in a gas or vapor

Q. 23. Lumen/watt is the unit of
A : Light flux
B : Luminous intensity
C : Brightness
D : Luminous efficiency.

Luminous efficiency.

Q. 24. Candela is-the unit for
A : Light flux
B : Luminous intensity
C : Brightness
D : Luminous efficiency.

Luminous intensity

Q. 25. Which gas is sometimes used in filament lamps ?
A : Argon
B : Krypton
C : Nitrogen
D : Carbon dioxide.

Argon

Q. 26. Which bulb operates on lowest power ?
A : Night bulb
B : Neon bulb
C : GLS bulb
D : Torch bulb.

Torch bulb.

Q. 27. The output of a tungsten filament lamp depends on
A : size of lamp
B : size of shell
C : temperature of filament
D : all of the above.

temperature of filament

Q. 28. A zero watt lamp consumes
A : no power
B : about 5 to 7 W power
C : about 15 to W power
D : about 25 to 30 W power.

about 5 to 7 W power

Q. 29. Melting temperature of tungsten is
A : 2000Â°K
B : 2500Â°K
C : 2655Â°K
D : 3655Â°K.

3655Â°K.

Q. 30. The life of incandescent lamp is expected to be
A : 100 hours
B : 200 hours
C : 1000 hours
D : 10000 hours.

1000 hours

Q. 31. The source of illumination for a cinema projector is
A : Incandescent lamp
B : Mercury vapor lamp
C : Sodium lamp
D : Carbon arc lamp.

Carbon arc lamp.

32. Sodium vapor lamps need ionization potential of about
A : 5 volts
B : 50 volts
C : 100 volts
D : 112 volts.

5 volts

Q. 33. When a sodium vapor lamp is switched on, initially the color is
A : Pink
B : Yellow
C : Green
D : Blue.

Pink

Q. 34. In a sodium vapor lamp the discharge is first started in the
A : neon gas
B : nitrogen gas
(‘C) argon gas
D : krypton gas.

neon gas

Q. 35. A auto transformer used with sodium vapor lamp should have
A : high efficiency
B : high step-up ratio
C : high step-down ratio
D : high leakage reactance.

high leakage reactance.

Q. 36. The capacitor used in auto transformer circuit for sodium vapor lamps, is for
A : protection against accidental power failure
B : controlling illumination level of the lamp
C : for regulating discharge voltage
D : for improving the power factor of the circuit.

for improving the power factor of the circuit.

Q. 37. A mercury vapor lamp gives
A : pink light
B : yellow light
C : greenish blue light
D : white light.

greenish blue light

Q. 38. Under the influence of fluorescent lamps sometimes the wheels of rotating machinery appear to be stationary. This is due to the
A : fluctuations
B : luminescence effect
C : stroboscopic effect
D : low power factor.

stroboscopic effect

Q. 39. Power factor is highest in case of
A : Mercury arc lamp
B : Sodium vapor lamps
C : Tube lights
D : GLS lamps.

GLS lamps.

Q. 40. Which of the following electric discharge lamp gives highest lumens/watt
A : Sodium vapor lamp
B : Neon lamp
C : Mercury lamp at low pressure
D : Mercury vapor at high pressure.

Sodium vapor lamp

Q. 41. The solid angle subtended at the center of a hemisphere of diameter D will be
A : 4Ï€D
B : 2Ï€D
C : 2Ï€
D : 4Ï€.

2Ï€

Q. 42. Which one of the following is a cold cathode lamp ?
A : Sodium lamp
B : Neon lamp
C : GSL lamp
D : Tube light.

Neon lamp

Q. 43. In a mercury vapor lamp light red objects appear black due to
A : high wavelength of red objects
B : color mixing
C : absence of red light from lamp radiation
D : absorption of red light by the lamp radiation.

absence of red light from lamp radiation

Q. 44. The flicker effect of fluorescent lamp is more pronounced at
A : lower voltages
B : higher voltages
C : lower frequencies
D : higher frequencies.

lower frequencies

Q. 45. The frequency of flickers in a fluorescent lamp at 220 V, 50 Hz supply will be
A : 25 per second
B : 50 per second
C : 100 per second
D : 220 per second.

100 per second

Q. 46. Wavelength of green color is nearly
A : 4000 A
B : 4500 A
C : 5000 A
D : 5500 A.

5500 A.

Q. 47. One Angstrom is
A : 10^-6 meter
B : 10^-8 meter
C : 10^-8 cm
D : 10^-8 mm.

10^-8 cm

Q. 48. Which of the following color has wave-length between green and color ?
A : Yellow
B : Blue
C : Violet
D : None.

Yellow

Q. 49. The purpose of providing a choke in a tube light is
A : to eliminate corona effects
B : to avoid radio interference
C : to improve power factor
D : to limit current to appropriate value.

to limit current to appropriate value.

Q. 50. A 60 W lamp given a luminous flux of 1500 lumen. Its efficiency is
A : 1500 lumen/watt
B : 250 lumen/watt
C : 25 lumen/watt
D : 2.5 lumen/watt.

25 lumen/watt

Q. 51. One lux is the same as
A : one lumen/sq. cm
B : one lumen/sq. m
C : one lumen/100 sq. m
D : one lumen/1000 sq. m.

one lumen/sq. m

Q. 52. The vacuum inside an incandescent lamp is of the order of
A : 10^-2 mm Hg
B : 10^-3 mm Hg
C : 10^-4 mm Hg
D : 10^-5 mm Hg.

10^-4 mm Hg

Q. 53. Which of the following application does not need ultra-violet lamps ?
A : Medical purposes
B : Aircraft cockpit dashboard lighting
C : Car lighting
D : Blue print machines.

Car lighting

Q. 54. When using ultra-violet lamps the reflector for maximum should be made of
A : aluminium
B : copper
C : leaf
D : glass.

aluminium

Q. 55. Which of the following combination of gas is filled in lamp and the resulting color is incorrect?
A : Neon-red
B : Nitrogen-buff
C : Carbon dioxide – day light white
D : Magnesium-white.

Magnesium-white.

Q. 56. Which of the, following vapors/gas will give yellow color in a filament lamp ?
A : Helium
B : Mercury
C : Sodium
D : Magnesium.

Sodium

Q. 57. Which of the following phosphor produces green color
A : Zinc silicate
C : Magnesium tungstate
D : Calcium halo phosphate.

Zinc silicate

Q. 58. If d is the distance of a surface from a source, the illumination of the surface will var as
A : d
B : 2d
C : 1/d
D : 1/ d^ 2

1/ d^ 2

Q. 59. The level of illumination on surface least depends on
A : candle power of the source
B : distance of the source
C : type of reflector used
D : ambient temperature.

ambient temperature.

Q. 60. The level of illumination from a 100 W incandescent lamp will not increase by
A : increasing the supply voltage
B : increasing filament temperature
C : increasing glass shell diameter.
D :

increasing glass shell diameter.

Q. 61. The rate of evaporation of tungsten filament in a lamp depends on
A : glass shell diameter
B : exhaust tube diameter
C : vapor pressure inside
D : none of the above.

vapor pressure inside

Q. 62. A gas filled filament bulbs, the gas used is
A : oxygen
B : helium
C : nitrogen
D : ozone.

nitrogen

Q. 63. Heat from the filament of a lamp is transmitted to the surrounding- mainly through
A : conduction
B : convection
D :

Q. 64. In a fluorescent tube circuit, choke acts as
A : starter
B : power factor improving device
C : source of heat
D : current limiting device.

current limiting device.

Q. 65. When a fluorescent lamp is to be operated on dc which of the following additional device must be incorporated in the circuit ?
A : Condenser
B : Transformer
C : Resistance
D : Inductance.

Resistance

Q. 66. For same rating the amount of radiant heat produced in which of the following lamp is the least ?
A : Fluorescent lamp
B : Filament lamp
C : Sodium vapor lamp
D : Mercury vapor lamp.

Fluorescent lamp

Q. 67. The amount of radiant heat produced by a fluorescent lamp is nearly what percent of that of a filament lamp of same rating
A : 80%
B : 60%
C : 40%
D : 20%.

20%.

Q. 68. Which of the following lamp gives nearly ultra-violet light ?
A : Vacuum type filament lamp
B : Nitrogen filed filament lamp
C : Argon filled filament lamp
D : Carbon arc lamp.

Carbon arc lamp.

Q. 69. Luminous flux is
A : rate of energy radiation in the form of light waves
B : light energy radiated by sun
C : part of light energy, radiated by sun which is received on earth
D : none of the above.

rate of energy radiation in the form of light waves

Q. 70. Match the following Column I Column II
a : Luminous flux (i) Candela
b : Luminous (ii) Candle power x intensity Solid angle
c : Lumen (iii) Lumens/W steredians
d : Candle power (iv) Lumens.
A : a-(i), b-(ii), c-(iii),d-(iv)
B : a-(iv), b-(i), c-(ii), d-(iii)
C : a-(i), b-(iv), c-(ii), d-(iii)
D : a – (iv), b – (iii), c- (i), d – (ii).