illumination Multiple Choice Questions and Answers (MCQ)

In this article, we shared the illumination multiple choice questions and answers for electrical and electronics engineers.

illumination Multiple Choice Questions

illumination Multiple Choice Questions and Answers

The below list provides all the multiple-choice questions related to electrical illumination.

Answers are available at the bottom of the article.

1. In lighting circuit using filament lamps 1% voltage drop results into

A)15 percent loss in the light output
B)3.5 percent loss in the light output
C)1.5 percent loss in the light output
D)no loss of light

2. Which of the following bulbs operates on the least power?

A)Neon bulb
B)GLS bulb
C)Night bulb
D)Torch bulb

3. In a sodium vapour lamp, the function of the leak transformer is

A)None of these answers
B)to stabilize the arc
C)both to stabilize the arc and to reduce the supply voltage
D)to reduce the supply voltage

4. For the same lumen output, the running cost of the fluorescent lamp is

A)more than that of filament lamp
B)any of these answers
C)equal to that of filament lamp
D)less than that of filament lamp

5. Illumination of one lumen per square metre is called

A)foot candle
D)lumen metre

6. Stroboscopic effect due to use of discharge lamps in workshops results in moving machinery appearing

B)stationary running in reverse direction
C)stationary running slow
D)all of these answers

7. In a sodium vapour lamp, neon gas

A)change the colour of light
B)prevents the vaporization of filament
C)acts as a shield around the filament
D)assists in developing enough heat to vaporize the sodium

8. The filament of a GLS lamp is made of


9. In houses the illumination is in the range of

A)10-20 lumens/watt
B)2-5 lumens/watt
C)60-65 lumens/watt
D)35-45 lumens/watt

10. On which of the following factors does the depreciation or maintenance factor depend?

A)Ageing of the lamp
B)Type of work carried out at the premises
C)Lamp cleaning schedule
D)All of these answers

11. What percentage of the input energy is radiated by filament lamps?

A)25 to 30 percent
B)2 to 5 percent
C)40 to 50 percent
D)10 to 15 percent

12. Which gas can be filled in GLS lamps?

A)Carbon dioxide
D)Any inert gas

13. Desired illumination level on the working plane depends upon

A)whether the object is stationary or moving
B)whether the object is to be seen for longer duration or shorter duration of time
C)age group of observers
D)size of the object to be seen and its distance from the observer
E)all of these answers

14. A reflector is provided to

A)all of these answers
B)protect the lamp
C)avoid glare
D)provide better illumination

15. For normal reading the illumination level required is around

A)20-40 lumens /​​m2
B)200-300 lumens /​​m2
C)400-500 lumens /​​m2
D)60-100 lumens /​​m2

16. Candela is the unit of which of the following?

C)Luminous intensity
D)Luminous flux

17. Which of the following instruments is used for the comparison of candle powers of different sources?

A)Bunsen meter.
C)Candle meter

18. Which of the following applications does not need ultraviolet lamps?

A)Blue print machines
B)Car lighting
C)Aircraft cockpit dashboard lighting
D)Medical purposes

19. The unit of luminous flux is

A)watt /​m2
D)lumen /​m2

20. When an electric bulb is broken it produces a bang, this is due to

A)pressure inside is equal to that outside
B)vacuum inside the bulb
C)none of these answers
D)pressure of air in the bulb

21. The tungsten filament lamps when compared with fluorescent tubes have all the following advantages except

A)less costly
B)more brightness
C)simple installation
D)longer life

22. Luminous flux is

A)the light energy radiated by sun
B)none of these answers
C)the rate of energy radiation in the form of light waves
D)the part of light energy, radiated by sun, which is received on the earth

23. In incandescent lamps, coiled coil filaments are used for

A)none of these answers
B)higher wattage lamps
C)gas filled lamps
D)coloured lamps
E)low wattage lamps

24. Glare is reduced by

A)all of these answers
B)using diffusers
C)using reflectors to cut-off the light at certain angle
D)increasing the height of the lamp

25. Which of the following statements is correct?

A)Light consists of shooting particles
B)Light consists of electromagnetic waves
C)Light is a form of heat energy
D)Light is a form of electrical energy

26. A solid angle is expressed in terms of _____


27. Sky appears blue because of

C)scattering of light over dust particles

28. In fluorescent tubes ballast resistance is connected in series with the choke

A)to reduce radio interference
B)to reduce stroboscopic effects
C)when supply frequency is low
D)when tube operates on D.C. supply

29. Which of the following lamps is the cheapest for the same wattage?

A)Mercury vapour lamp
B)GLS lamp
C)Sodium vapour lamp
D)Fluorescent tube

30. In an incandescent lamp bird cage filament is usually used in a vacuum bulb so as to

A)reduce the oxidation phenomenon
B)reduce the convection losses
C)increase the life span of the filament
D)have uniform radiations

31. In the case of ____ least illumination level is required.

A)drawing offices
B)skilled bench work
C)hospital wards
D)fine machine work

32. ____ is a cold cathode lamp.

A)Sodium vapour lamp
B)Neon lamp
C)Mercury vapour lamp
D)Fluorescent lamp

33. ____ cannot sustain much voltage fluctuations.

A)Mercury vapour lamp
B)Fluorescent lamp
C)Incandescent lamp
D)Sodium vapour lamp

34. Colour of light depends upon

A)wave length
B)speed of light
C)both frequency and wave length

35. Filament lamps operate normally at a power factor of

A)0.8 lagging
C)0.8 leading
D)0.5 lagging

36. The function of capacitor across the supply to the fluorescent tube is primarily to

A)stabilize the arc
B)reduce the starting current
C)reduce the noise
D)improve the supply power factor

37. In case of ____ power factor is the power factor is the

A)mercury arc lamps
B)sodium vapour lamps
C)tube lights
D)GLS lamps

38. For the same power output

A)none of these answers
B)both low and high voltage rated lamps will be equally sturdy
C)low voltage rated lamps will be more sturdy
D)high voltage rated lamps will be more sturdy

39. Most affected parameter of a filament lamp due to voltage change is

B)luminous efficiency
D)light output

40. “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)Lambert’s cosine law
C)Bunsen’s law of the illumination
D)Macbeth’s law of illumination

41. The vapour discharge tube used for domestic lighting has

A)one filament
B)three filaments
C)two filaments
D)no filament

42. Soft shadows are produced by

A)none of these answers
B)using surface source of light instead of point source of light
C)increasing the number of lamps
D)both using surface source of light instead of point source of light and increasing the number of lamps

43. When a fluorescent lamp is to be operated on D.C. which of the following additional devices must be incorporated in the circuit?


44. Filament lamp at starting will take current

A)less than its full running current
B)equal to its full running current
C)more than its full running current
D)none of these answers

45. The colour of sodium vapour discharge lamp is

A)bluish green

46. A poor man for his kitchen will make use of

A)incandescent lamp
B)sodium vapour lamp
C)fluorescent tube
D)high pressure mercury vapour lamp

47. Co-efficient of utilisation depends upon

A)size of the room
B)all of these answers
C)colour of ceiling
D)colour of the walls

48. The purpose of coating the fluorescent tube from inside with white power is

A)to change the colour of light emitted to white
B)to improve the appearance
C)to improve its life
D)to increase the light radiations to secondary emissions

49. _____ will need lowest level of illumination

B)Railway platform
D)Fine engravings

50. In the fluorescent tube circuit the function of choke is primarily to

A)reduce the starting current
B)reduce the flicker
C)initiate the arc and stabilize it
D)minimise the starting surge

51. A mercury vapour lamp gives ____ light.

B)greenish blue

52. The level of illumination on a surface least depends on

A)ambient temperature
B)type of reflector used
C)distance of the source
D)candle power of the source

53. ____ does not have separate choke

A)Mercury vapour lamp
B)Sodium vapour lamp
C)Fluorescent lamp
D)All of these answers

54. Due to moonlight, illumination is nearly

A)300 lumens /​​m2
B)0.3 lumen /​​m2
C)3000 lumens /​​m2
D)30 lumens /​​m2

55. For precision work the illumination ‘level required is of the order of

A)200-400 lumens /​​m2
B)500-1000 lumens /​​m2
C)10-25 lumens /​​m2
D)50-100 lumens /​​m2

56. Reflectors are provided with slits at the top to

A)reduce heating effect
B)all of these answers
C)introduce chimney effect for cleaning
D)reduce colour contrast

57. Which of the following is present inside the fluorescent tube?

A)Argon and​​ CO2
B)Helium and oxygen
C)Mercury vapour
D)Argon and neon

58. Luminous efficiency of a fluorescent tube is

A)10 lumens/watt
B)20 lumens/watt
C)60 lumens/watt

59. The gas filled in vacuum filament lamps is

A)none of these answers

60. In electric discharge lamps for stabilizing the arc

A)a reactive choke is connected in series with the supply
B)a condenser is connected in parallel to the supply
C)a variable resistor is connected in the circuit
D)a condenser is connected in series to the supply

61. Fine diameter tungsten wires are made by

C)wire drawing

62. Due to which of the following reasons the light of a tube appears cooler than that of a bulb?

A)Tube consumer less power
B)Tungsten is not used in the tube
C)None of these answers
D)Surface area of the tube is more than that of bulb
E)Tube is painted with milky colour

63. The flicker effect of fluorescent lamps is more pronounced at

A)higher voltages
B)lower frequencies
C)lower voltages
D)higher frequencies

64. Which of the following is not the standard rating of GLS lamps?

D)40 W

65. Carbon arc lamps are commonly used in

A)cinema projectors
B)street lighting
C)domestic lighting

66. Sometimes the wheels of rotating machinery, under the influence of fluorescent lamps appear to be stationary. This is due to the

A)stroboscopic effect
C)low power factor
D)luminescence effect

67. In electric discharge lamps light is produced by

A)heating effect of current
B)magnetic effect of current
C)ionisation in a gas or vapour
D)cathode ray emission

68. A substance which change its electrical resistance when illuminated by light is called

B)none of these answers

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