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 $



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