Sources of Light 4

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Questions Electrician and Wireman: Sources of Light 4

Subject: Sources of Light 4

Part 4: Objective questions and answers of Sources of Light


Q1. A 250 v lamp has a total flux of 3000 lumens and takes a current of 0.8 ampere from 250 v mains. Its luminous efficiency is

a) 12 lumens per watt

b) 9.6 lumens per watt

c) 15 lumens per watt

d) 240 lumens per watt


Q2. What is the purpose of the choke after the fluorescent tube is just lighted to its full brightness?

a) For supplying a higher operating current

b) Smoothing the sinusoidal operating current

c) Limiting the current flowing through the fluorescent tube filaments

d) Heating the filaments continuously during operation


Q3. Colour of light depends upon

a) Velocity of light

b) Frequency

c) Wave length

d) Both b and c


Q4. A perfect diffuser surface is one that

a) Transmits ail the incident light

b) Absorbs all the incident light

c) Diffuses all the incident light

d) All of the above


Q5. The study of illumination involves the:

a) Study of lighting and wiring systems

b) Designing of a lighting system

c) Calculating of wiring materials required in wiring

d) Study of photometry


Q6. The luminous-flux emitted in unit solid angle by a light source having a luminousintensity of one candela Is called:

a) Illumination

b) Luminance

c) One lumen

d) One lux


Q7. The illumination at a point of a surface is the luminous-flux per unit area of the surface and its unit is:

a) Lux

b) Lumen

c) Candela

d) Watt


Q8. Which position mb type high pressure mercury vapour lamps are operated?

a) Vertical

b) Inclined

c) Horizontal

d) Any position


Q9. How stroboscopic effect in industrial twin tube light fitting is reduced?

a) Connecting capacitor parallel to supply

b) Connecting capacitor in series with supply

c) Connecting capacitor in series with one tube light

d) Connecting two capacitors in series to each tube light


Q10. What is the purpose of igniter in high pressure sodium vapour lamp circuit?

a) Decreases the starting current

b) Increases the running voltage

c) Decreases the running current

d) Generates high voltage pulse at starting


Q11. Why the outer tube of a high pressure metal halide lamp made of boro silicate glass?

a) Increase the lighting effect

b) Withstand heavy temperature

c) Withstand atmospheric pressure

d) Reduce the ultra violet radiation from lamp


Q12. What is the unit of luminous flux?

a) Lux

b) Lumen

c) Candela

d) Lumen/m^2


Q13. How the rate of evaporation in a vacuum bulb is reduced?

a) Filling inert gas

b) Producing arc in bulb

c) Reducing filament resistance

d) Increasing filament resistance


Q14. Which device provides ignition voltage and act as choke in hpsv lamp?

a) Arc tube

b) Sodium vapour

c) Leak transformer

d) High pressure aluminum oxide


Q15. Which is the cold cathode lamp?

a) Halogen lamp

b) Neon sign lamp

c) Fluorescent lamp

d) Mercury vapour lamp


Q16. The rating of i.c.d.p. switch used in a neon-sign tube should be :

a) 15 a, 250 v

b) 15 ma, 230 v

c) 15ma, 1000 v

d) 15 a, 1000 v


Q17. Upon which one of the following, the current flow through the neon-sign tubes depends?

a) The diameter of the tube

b) The gases in the tube

c) The length of the tube

d) The colour of the tube


Q18. The ignition voltage of sodium lamp varies from…….

a) 400 to 600 v

b) 400 to 550 v

c) 400 to 500 v

d) 400 to 450 v


Q19. The starter of a fluorescent tube lamp has been removed from its holder after the tube is lighted what will happen to the function of the tube lamp?

a) Tube lamp will begin to flicker

b) Tube lamp will go out immediately

c) Tube will operate normally

d) Tube will begin to hum very much


Q20. Which one of the basic fluorescent powder is used in neon sign lamp to get blue colour?

a) Cadmium silicate

b) Calcium silicate

c) Calcium tungstate

d) Zinc silicate


Part 4: Objective questions and answers of Sources of Light


Q1. Answer c

Q2. Answer: c

Q3. Answer d

Q4. Answer d

Q5. Answer b

Q6. Answer c

Q7. Answer a

Q8. Answer d

Q9. Answer c

Q10. Answer d

Q11. Answer d

Q12. Answer b

Q13. Answer a

Q14. Answer c

Q15. Answer b

Q16. Answer: a

Q17. Answer: a

Q18. Answer: a

Q19. Answer: c

Q20. Answer: c

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