Optics Question 498
Question: 1% of light of a source with luminous intensity 50 candela is incident on a circular surface of radius 10 cm. The average illuminance of surface is
Options:
A) 100 lux
B) 200 lux
C) 300 lux
D) 400 lux
Show Answer
Answer:
Correct Answer: B
Solution:
$ \varphi =4\pi L=200\ \pi $ lumen.
So $ I=\frac{\varphi }{100A}=\frac{200\pi }{100\times \pi r^{2}}=\frac{2}{{{(0.1)}^{2}}} $ = 200 lux.
