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About 5% of the power of a 100 W light bulb is converted to visible radiation. What is the average intensity of visible radiationa.at a distance of 1m from the bulb b. at a distance of 10mAssume that the radiation is emitted isotropically and neglect reflection.

Answer»

SOLUTION :a.`A=4pi r^(2)=4xx3.14xx1^(2)m^(2)`
`I=("POWER")/("Area")=(100xx 5//100)/(4xx3.14xx1^(2))=0.4 WM^(-2)`
B.`I=(100xx 5//100)/(4xx3.14xx10^(2))=0.004 Wm^(-2)`


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