Question 351: Properties of Matter

Question

A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be

Accepted Answer

Given r
1
= 12 cm , r
2
= 6 cm
T
1
= 500 K and T
2
= 2 ÃÂ 500 = 1000 K
P
1
= 450 watt
Rate of power loss $$P \propto {r^2}{T^4}$$
$${{{P_1}} \over {{P_2}}} = {{r_1^2T_1^4} \over {r_2^2T_2^4}}$$
$${P_2} = {P_1}{{r_1^2T_1^4} \over {r_2^2T_2^4}}$$
Solving we get,   P
2
= 1800 watt

Answer

450

Answer

1000

Answer

1800

Answer

225

Properties of Matter

A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be

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