Q136 / 160 · TS EAMCET 2024 (09 May Shift 2) · Physics

A solid sphere at a temperature $\mathbf{T ~ K}$ is cut in to two hemispheres. The ratio of energies radiated by one hemisphere to the whole sphere per second is

  • A
    $1: 1$
  • B
    $1: 2$
  • Correct answer
    C
    $3: 4$
  • D
    $1: 4$

Solution

From Stefan's law $\mathrm{E} \propto \mathrm{A}$ Initial area of hemisphere, $\mathrm{A}_1=4 \pi \mathrm{r}^2$ Final area of hemisphere, $A_2=2 \pi \mathrm{r}^2+\pi \mathrm{r}^2=3 \pi \mathrm{r}^2$ $\therefore \frac{E_2}{E_1}=\frac{3 \pi r^2}{4 \pi r^2}=\frac{3}{4}$

Hence, the correct answer is option: 'C'.

Relevant Questions