Illumination -- Electrical Engineering (MCQ) questions and answers

1. Which of the following statement id correct?

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

2. Luminous efficiency of a fluoresent tube is:

A.10 lumens/watt
B. 20 lumens/watt
C. 60 lumens/watt
D. 40 lumens/watt

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

A. Wavelength
B. Luminous flux
C. Luminous intensity
D. Fequency

4. Illumination of one lumen per square meter is called ____________

A. Lumen meter
B. Lux
C. foot candle
D.candela

5. A solid angle is expressed in term of __________

A. radians/meter
B. radians
C. degree
D. Steradians

6. The unit of luminous flux is_____________

A.watt
B.lumens/m^2
C.watt/m^2
D. Lumen

7. Filament lamps operate normally at a power factor of

A. unity
B. 0.8 leading
C. 0.8 lagging
D. 0.5 lagging

8.The filament of a GLS lamp is made of

A. copper
B.carbon
C. aluminium.
D. tungsten
Explain:-
GLS:

GLS lamp stands for General Lighting Service; Standard GLS lamp is an incandescent lamp with a coiled tungsten filament

Incandescent lamps produce light as a result of the heating effect of an electrical current flowing through a filament wire

At the centre of the lamp there is a filament. Any inert gas can be filled inside the bulb. Normally, argon with nitrogen is used.

As it is a highly resistive circuit, the power factor of GLS lamp is very high and ideally, it is unity

In the case of frosted GLS lamps, the frosting of the shell is done by acid etching

Acid etching creates a very smooth, glossy and satin finish and the acid-etched lamp is maintenance-free as it does not show dirt marks or fingerprints.

9. Fine diameter tungsten wires are made by

A. wire drawing.
B. turning
C.swaging
D. compressing

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

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

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

A. Sodium vapour lamp.
B. Mercury vapour lamp
C. fluorescent tube
D. GLS lamp

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

A. 40 W
B. 15 W
C. 75 W
D. 100 W

13.
"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. Bunsen's law of the illumination
C.Lambert's cosine law
D.Macbeth's law of illumination

14. The colour of sodium vapour discharge lamp is

A. bluish green
B. yellow
C. pink
D. red

15. Carbon arc lamps are commonly used in

A.photography
B.street lighting
C.domestic lighting
D.cinema projectors

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

A.Lamp cleaning schedule
B. Agening of the lamp
C.Type of work carried out at the premises
D. All of the above factors

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

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

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

A.equal to that of filament lamp
B. any of the above
C. more than that of filament lamp
D.less than that of filament lamp

19. For the same power output

A. low voltage rated lamps will be more sturdy
B.high voltage rated lamps will be more sturdy
C. both low and high voltage rate lamps will be equal sturdy
D.None of these

20. The cost of a fluorescent lamp is more than that of incandescent lamp because of which of the following factors ?

A. More labour is required in its manufacturing
B.Number of components used is more
C. All of the above factors
D. Quantity of glass used is more