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.



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