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About 5% of the power of a 100 W light b...

About `5%` of the power of a `100 W` light bulb is converted to visible radiation. What is the average intensity of visible radiation
(a) at a distance of `1 m` from the bulb?
(b) at a distance of `10 m` ?
Assume that the radiation is esmitted isotropically and neglect reflection.

Text Solution

Verified by Experts

(a) Intensity, `I=("power of visible light") /("area")=(100xx(5//100))/(4pi(1)^2)=0.4W//m^2`
(b) `I=(100xx(5//10))/(4pi(10)^2)=4xx10^-3W//m^2`
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