Electric Illumination MCQs | Electricalvoice

Electric Illumination MCQs

1. Radiant efficiency of the luminous source depends on

(A) the wavelength of light rays
(B) the temperature of the source
(C) the shape of the source
(D) all of the above

Answer
Answer. B

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

Answer
Answer. A

3. Carbon arc lamps are commonly used in

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

Answer
Answer. C

4. The unit of solid angle is

(A) solid angle
(B) radian
(C) steradian
(D) candela.

Answer
Answer. C

5. Candela is the unit of

(A) Luminous flux
(B) Luminous intensity
(C) Wavelength
(D) None of the above.

Answer
Answer. B

6. The unit of luminous flux is

(A) steradian
(B) candela
(C) lumen
(D) lux.

Answer
Answer. C

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.

Answer
Answer.D

8. Which curve represents the life of the lamp?

(A) curve A
(B) curve B
(C) curve C
(D) curve D.

Answer
Answer. B

9. Illumination level required for precision work is around

(A) 50 lm/m2
(B) 100 lm/m2
(C) 200 lm/m2
(D) 500 lm/m2.

Answer
Answer.D

10. Which of the following will need the highest level of illumination?

(A) Proof reading
(B) Bed rooms
(C) Hospital wards
(D) Railway platforms.

Answer
Answer. A

11. Which of the following will need the lowest level of illumination?

(A) Displays
(B) Fine engraving
(C) Railway platform
(D) Auditoriums.

Answer
Answer. C

12. Which of the following lamp gives nearly monochromatic light?

(A) Sodium vapor lamp
(B) GLS lamp
(C) Tube light
(D) Mercury vapor lamp.

Answer
Answer. A

13. 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.

Answer
Answer.D

14. 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.

Answer
Answer.D

15. One lumen per square meter is the same as

(A) One lux
(B) One candela
(C) One foot candle
(D) One lumen meter.

Answer
Answer. A

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