Q160 / 180 · KCET 2009 · Physics
The amount of heat energy radiated by a metal at temperature $\mathrm{T}$ is $\mathrm{E}$. When the temperature is increased to 3T, energy radiated is
- Correct answerA$81 \mathrm{E}$
- B9E
- C$3 \mathrm{E}$
- D$27 \mathrm{E}$
Solution
According to Stefan's law
$$
E \propto T^{4}
$$
$$
\therefore \quad \frac{\mathrm{E}^{\prime}}{\mathrm{E}}=\left(\frac{3 \mathrm{~T}}{\mathrm{~T}}\right)^{4} \text { or } \mathrm{E}^{\prime}=81 \mathrm{E}
$$
Hence, the correct answer is option: 'A'.