Optics Question 476
Question: If luminous efficiency of a lamp is 2 lumen/watt and its luminous intensity is 42 candela, then power of the lamp is
[AFMC 1998]
Options:
A) 62 W
B) 76 W
C) 138 W
D) 264 W
Show Answer
Answer:
Correct Answer: D
Solution:
Luminous flux $ =4\pi \ L $
$ =4\times 3.14\times 42\ =\ 528 $
Lumen Power of lamp $ =\frac{Luminous\ flux}{Luminousefficiency} $
$ =\frac{528}{2}=264\ W $
