TS EAMCET · Physics · Thermal Properties of Matter
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 \(1: 2\)
- C \(3: 4\)
- D \(1: 4\)
Answer & Solution
Correct Answer
(C) \(3: 4\)
Step-by-step Solution
Detailed explanation
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, \(A_2=2 \pi \mathrm{r}^2+\pi \mathrm{r}^2=3 \pi \mathrm{r}^2\) \(\therefore \frac{E_2}{E_1}=\frac{3 \pi r^2}{4 \pi r^2}=\frac{3}{4}\)
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