1. The unit of solid angle is
a)Solid Angle
b)Radian
c)Steradian
d)Candela
Ans: c
2. Candela is the unit of
a)Luminous flux
b)Luminous intensity
c)Wavelength
d)None of the above
Ans: b
3. The practical luminous efficiency of the sodium vapour lamp is of the order of
a) 25 to 40 lumens per watt
b) 40 to 45 lumens per watt
c) 45 to 50 lumens per watt
d) 60 to 67 lumens per watt
Ans: c
4. In illumination what is lamp efficiency?
a)Lumen – watt
b)Lumens/watt
c)Total flux in lumen / 2π
d)Total flux in lumen / 4π
Ans: b
5. The radiant efficiency of the luminous source depends on
a)The shape of the source
b)The temperature of the source
c)The wavelength of the light rays
d)All of the above
Ans: b
Radiant efficiency of the luminous source is defined as the ratio of
“energy radiated in the form of light” to “total energy radiated out of the
hot body” and it depends on the temperature of the source
6. Carbon arc lamps are commonly used in
a)Domestic lighting
b)Street lighting
c)Cinema Projector
d)Photography
Ans: c
7. The unit of luminous flux is
a)Steradian
b)Candela
c)Lumen
d)Lux
Ans: c
8. Illumination level required for precision work is around
a)50 lm/m2
b)100 lm/m2
c)200 lm/m2
d)500 lm/m2
Ans: d
9. Which of the following lamps gives nearly monochromatic light?
a)Sodium vapor lamp
b)GLS Lamp
c)Tube light
d)Mercury vapor lamp
Ans: a
10. The 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
Ans: d
11. One lumen per square meter is the same as
a)One lux
b)One Candela
c)One foot candle
d)One lumen meter
Ans: a
12. The output of a tungsten filament lamp depends on
a)Size of lamp
b)Size of shell
c)Temperature of filament
d)All of the above
Ans: c
13. Light is produced in electric discharge lamps by
a)Heating effect of current
b)Magnetic effect of current
c)Ionization in a gas or vapor
d)Carbon electrodes
Ans: c
14.Lumen/watt is the unit of
a)Light Flux
b)Luminous Intensity
c)Brightness
d)Luminous Efficiency
Ans: d
15. In fluorescent tubes, ballast resistance is connected in series with the choke
a)When supply frequency is low
b)To reduce radio interference
c)When tube operates on dc supply
d)To reduce stroboscope effects
Ans: c
14.Neon gas in sodium vapor lamp
a)Changes the color of light
b)Acts as a shield around the filament
c)Assists in developing enough heat to vaporize the sodium
d)Prevents vaporization of filament
Ans: c
15. A lamp has a mean spherical candle power of 25, the total flux of light from the lamp is
a)25 lumens
b)25 π lumens
c)314 lumens
d)625 lumens
Ans: c This relationship between candlepower and lumens can be expressed mathematically as follows:
L = 12.57CM
Where
L = Lumen
CM = mean spherical candlepower
L = 12.57 × 25 = 314.25
16. A gas-filled filament bulbs, the gas used is
a)Oxygen
b)Helium
c)Ozone
d)Nitrogen
Ans: d
17.LED lamp have a general life expectancy of
a)1000 hrs
b)5000 hrs
c)15000 hrs
d)50000 hrs
Ans: d
18.A 200 candle power lamp is hung 4 m above the center of circular area of 5 m diameter. The illumination at centre of the area is
a)13.5 lux
b)12.5 lux
c)17.5 lux
d)18.5 lux
Ans: b
19. The work of ballast in a fluorescent tube is to
a)limit the flow of current
b)provide a kick start when voltage is induced
c)both ‘a’ and ‘b’
d)None of these
Ans: c
20.The illumination at a point 5 meters below a lamp in 6 lux. The candle power of the lamp is
a) 30
b)140
c) 150
d)200
Ans: c
21. __________ lamp is also known as quick start or “instant start”
fluorescent tube
a)Sodium vapor lamp
b)Startless fluorescent lamp
c)Mercury vapor lamp
d)Neon Lamp
Ans: b
22. The heat from the filament of a lamp is transmitted to the surrounding-
mainly through a)Conduction
b)Convection
c)Radiation
d)No heat is transferred
Ans: c
23. A fluorescent tube of 20W has a luminous flux of:
a)75 lumens
b)950 lumens
c)14 lumens
d)325 lumens
Ans: b
24. Which of the following called as fluorescent material?
a) Phosphorus
b) Potassium
c) Uranium
d) Helium
Ans: a
25. Power factor is highest in case of
a)Mercury arc lamp
b)Sodium vapor lamps
c)Tube lights
d)GLS lamps
Ans: d
26. The function of inert gas in filament lamp is
a) Increase the illumination
b) Decrease the power consumption
c) Minimize the effect of evaporation during service
d) Decrease the Clare
Ans: c
27.A 60 W lamp given a luminous flux of 1500 lumen. Its efficiency is
a)1500 lumen/watt
b)250 lumen/watt
c)25 lumen/watt
d)2.5 lumen/watt
Ans: c
28. Sodium vapor lamps need ionization potential of about
a)5 volts
b)50 volts
c)100 volts
d)112 volts
Ans: a
29. Arc can be produced by?
a)AC current only
b)DC current only
c)Either AC or DC current
d)All option are correct
Ans: c
30. In a fluorescent tube circuit, choke acts as
a)Starter
b)The power factor improving device
c)Source of heat
d)Current limiting device
Ans: d
31. Which of the following instruments is used for the comparison of candle powers of different sources?
a)Radiometer
b)Bunsen meter
c) Photometer
d) Candle meter
Ans: c
32.“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) Lambert’s cosine law
b) Planck’s law
c) Bunsen’s law of the illumination
d)Macbeth’s law of illumination
Ans: a
33. The function of the capacitor across the supply to the fluorescent tube is primarily to
a)stabilize the arc
b)reduce the starting current
c)Improve the supply power factor
d)Reduce the noise
Ans: c
34. The gas-filled in vacuum filament lamps is
a)Nitrogen
b)Argon
c) Air
d)none
Ans: d
“Failure is the opportunity to begin again more intelligently”
by: Henry ford
For detail explanation of each question you can watch this video..