In this article, we shared the illumination multiple choice questions and answers for electrical and electronics engineers.
illumination Multiple Choice Questions
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 |
| B) | lux |
| C) | candela |
| D) | lumen metre |
6. Stroboscopic effect due to use of discharge lamps in workshops results in moving machinery appearing
| A) | stationary |
| 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
| A) | aluminium |
| B) | copper |
| C) | tungsten |
| D) | carbon |
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 |
| B) | Oxygen |
| C) | Xenon |
| 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?
| A) | Frequency |
| B) | Wavelength |
| 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. |
| B) | Radiometer |
| C) | Candle meter |
| D) | Photometer |
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 |
| B) | watt |
| C) | lumen |
| 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 _____
| A) | degrees |
| B) | radians |
| C) | radians/metre |
| D) | steradians |
27. Sky appears blue because of
| A) | refraction |
| B) | reflection |
| C) | scattering of light over dust particles |
| D) | radiation |
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 |
| D) | frequency |
35. Filament lamps operate normally at a power factor of
| A) | 0.8 lagging |
| B) | unity |
| 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
| A) | life |
| B) | luminous efficiency |
| C) | wattage |
| 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?
| A) | Transformer |
| B) | Resistance |
| C) | Condenser |
| D) | Inductance |
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 |
| B) | pink |
| C) | yellow |
| D) | red |
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
| A) | Auditoriums |
| B) | Railway platform |
| C) | Displays |
| 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.
| A) | yellow |
| B) | greenish blue |
| C) | pink |
| D) | white |
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 |
| D) | lumens/watt |
59. The gas filled in vacuum filament lamps is
| A) | none of these answers |
| B) | nitrogen |
| C) | air |
| D) | argon |
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
| A) | compressing |
| B) | turning |
| C) | wire drawing |
| D) | swaging |
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?
| A) | 100W |
| B) | 75W |
| C) | 15W |
| D) | 40 W |
65. Carbon arc lamps are commonly used in
| A) | cinema projectors |
| B) | street lighting |
| C) | domestic lighting |
| D) | photography |
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 |
| B) | fluctuations |
| 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
| A) | photovoltaic |
| B) | none of these answers |
| C) | photoelectric |
| D) | photoconductive |
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