Optics Question 512
Question: Find the luminous intensity of the sun if it produces the same illuminance on the earth as produced by a bulb of 10000 candela at a distance 0.3 m. The distance between the sun and the earth is $ 1.5\times 10^{11}m $
Options:
A) $ 25\times 10^{22}cd $
B) $ 25\times 10^{18}cd $
C) $ 25\times 10^{26}cd $
D) $ 25\times 10^{36}cd $
Show Answer
Answer:
Correct Answer: C
Solution:
Illuminance produce by the sun $ =\frac{L}{{{(1.5\times 10^{11})}^{2}}} $
Illuminance produce by the bulb $ =\frac{10000}{{{(0.3)}^{2}}} $
According to problem $ \frac{L}{{{(1.5\times 10^{11})}^{2}}}=\frac{10000}{{{(0.3)}^{2}}} $
$ \Rightarrow L=\frac{2.25\times 10^{22}\times 10^{4}}{9\times {{10}^{-2}}} $
$ =25\times 10^{26}Cd $
