# ONLINE MCQ EE-ILLUMINATION 5

Q41. The unit of luminous flux is
A.  watt/m2
B.  lumen
C.  lumen/m2
D.  watt
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Q42. The colour of sodium vapour discharge lamp is
A.  red
B.  pink
C.  yellow
D.  bluish green
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Q43. A reflector is provided to
A.  protect the lamp
B.  provide better illumination
C.  avoid glare
D.  do all of the above
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Q44. ____ does not have separate choke
A.  Sodium vapour lamp
B.  Fluorescent lamp
C.  Mercury vapour lamp
D.  All of the above
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Q45. A substance which change its electrical resistance when illuminated by light is called
A.  photoelectric
B.  photovoltaic
C.  phatoconductive
D.  none of the above
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Q46. Luminous flux is
A.  the light energy radiated by sun
B.  the part of light energy, radiated by sun, which is received on the earth
C.  the rate of energy radiation in the form of light waves
D.  none of the above
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Q47. Sky appears blue because of
A.  refraction
B.  reflection
D.  scattering of light over dust parti­cles
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Q48. The level of illumination on a surface least depends on
A.  ambient temperature
B.  candle power of the source
C.  distance of the source
D.  type of reflector used
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Q49. Filament lamps operate normally at a power factor of
A.  0.5 lagging
B.  0.8 lagging
C.  unity
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Q50. Carbon arc lamps are commonly used in
A.  photography