Radiant energy from sun incident normally at surface of earth is 20, kcal/m^2-min . What would have

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10-2.Transmission of Heat

normal

The radiant energy from sun incident normally at the surface of earth is $20\, kcal/m^2-min$. What would have been the radiant energy incident normally on the earth if the sun had a temperature twice of the present one ......... $kcal/m^2-min$

A

$40$

B

$80$

C

$160$

D

$320$

Solution

$E \propto T^{4}$

$\frac{E_{1}}{E_{2}}=\left(\frac{T_{1}}{T_{2}}\right)^{4}$

$\frac{20}{\mathrm{E}}=\left(\frac{\mathrm{T}}{2 \mathrm{T}}\right)^{4}$

$E=320 \mathrm{kcal} / \mathrm{m}^{2}-\mathrm{min}$

Standard 11

Physics

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