First slide

Radiation

Question

All bodies radiate heat in proportion to the fourth power of temperature T. If a body (coated black) at 400 K surrounded by atmosphere at 300 K has cooling rate $r_{0}$ , the same body at 900 K, surrounded by the same atmosphere, will have cooling rate closest to

Moderate

A

$1296 r_{0} / 35$
B

$81 r_{0} / 16$
C

$16 r_{0}$
D

$4 r_{0}$

Solution

According to Stefan's law
$r_{0} = σ (400^{4} - 300^{4})$ and $r = σ (900^{4} - 300^{4})$
$∴ r = [\frac{(900^{4} - 300^{4})}{(400^{4} - 300^{4})}] r_{0} = 1296 r_{0} / 35$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App