Electric Illumination MCQ PDF

1. Light………

(a) is a form of heat energy.
(b) is a form of electrical energy.
(c) consists of electromagnetic waves.
(d) consists of shooting particles.

2. Radiant efficiency of the luminous source depends on

(a) temperature of the source.
(b) wavelength of light rays.
(c) shape of the source.
(d) all of the above.

3. A substance which changes its electrical resistance when illuminated by light is called

(a) photoconductive.
(b) photovoltaic.
(c) photoelectric.
(d) none of the above.

4. Materials which reflect all wavelength in the spectrum of light appear to be

(a) opaque.
(b) transparent.
(c) black to white.
(d) green to red.

5. An object, which appears red to the eyes, absorbs

(a) blue radiations.
(b) violet radiations.
(c) green radiations.
(d) all of the above.

6. The sensors in the eye are known as

(a) retina and antenna.
(b) wires and nerves.
(c) rodes and cones.
(d) none of the above.

7. The color temperature of daylight is about

(a) 100 K
(b) 200 K
(c) 500 K
(d) 600 K

8. Sky appears blue due to

(a) radiation.
(b) reflection.
(c) refraction.
(d) scattering of light over dust particles.

9. Color of light depends upon

(a) velocity of light.
(b) frequency.
(c) wavelength.
(d) both (b) and (c).

10. The wavelength of 5,500 ^oA will give light of

(a) green color.
(b) red color.
(c) orange color.
(d) yellow-green color.

11. Which of the following color has wavelength between blue and yellow ?

(a) Violet.
(b) Orange.
(c) Red.
(d) Green.

12. Luminous flux is

(a) the rate of energy radiation in the form of light waves.
(b) the part of light energy, radiated by Sun that is received on earth.
(c) measured in lux.

13. Candle power is

(a) the luminous flux emitted by the source per unit solid angle.
(b) the light radiating capacity of a source in a given direction.
(c) the unit of illumination.

14. Glare is caused due to

(a) excessive luminance.
(b) excessive lighting contrast in the field of vision.
(c) either (a) or (b).

15. A perfect diffuser surface is one that

(a) transmits all the incident light.
(b) absorbs all the incident light.
(c) diffuses all the incident light.
(d) all of the above.

16. The illumination at a surface due to a source of light placed at a distance ‘d’ from the surface varies as

(a) 1/d²
(b) 1/d
(c) d

17. The illumination at various points on a horizontal surface illuminated by the same source varies as

(a) cos θ
(b) cos²θ
(c) cos³θ
(d) 1/cos θ

18. The melting point of tungsten is

(a) 3,400°C
(b) 2,800°C
(c) 2,600°C
(d) 2,400°C

19. The vacuum inside an incandescent lamp is of the order of

(a) 10^-2 mm Hg
(b) 10^-4 mm Hg
(c) 10^-6 mm Hg
(d) 10^-8 mm Hg

20. The rate of evaporation of tungsten filament in a lamp depends upon

(a) exhaust tube diameter.
(b) glass shell diameter.
(c) vapor pressure inside.
(d) none of the above.