Rankers Physics

Heat Transfer - Radiation: Practice Problem & Solution

A black body is at 727°C. It emits energy at a rate which is proportional to
\[ \left( 727 \right)^{4}\]
\[ \left( 727 \right)^{2} \]
\[ \left( 1000 \right)^{4} \]
\[ \left( 1000 \right)^{2}\]

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Heat Transfer - Radiation. Understanding the underlying formula is key to arriving at the correct answer below:

The energy emitted by a black body is proportional to the fourth power of its absolute temperature, as per Stefan-Boltzmann Law:

\[
P \propto T^4
\]

Step 1: Convert temperature to kelvins

The temperature of the black body is \(727^\circ C\), which is:

\[
T = 727 + 273 = 1000\,K
\]

Step 2: Apply Stefan-Boltzmann Law

Since the energy emitted is proportional to \(T^4\):

\[
P \propto (1000)^4
\]

Thus, the rate of energy emission is proportional to \((1000)^4\).

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