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The emissive power of a sphere of area 0...

The emissive power of a sphere of area `0.07m^(2)` is 0.5 k cal/`m^(2)s`. The amount of heat radiated by the spherial surface in 20 second is

A

7 kcal

B

0.7 kcal

C

0.07 kcal

D

20 kcal

Text Solution

Verified by Experts

The correct Answer is:
B
`E=(Q)/(At)`
`therefore Q=EA t=0.5xx0.07xx20=0.7` kcal
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