Q. Two spheres made of same material have radii in the ratio 1:2. Both are at same temperature. Ratio of heat radiation energy emitted per second by them is
A) 1 : 2
B) 1 : 8
C) 1 : 4
D) 1 : 16
Explanation
(c) $Q = A\varepsilon\sigma T^{4} \Rightarrow Q \propto A \propto r^{2}\ \ \ \ \ \ \ \lbrack\because T =$ constant]
$\Rightarrow \frac{Q_{1}}{Q_{2}} = \frac{r_{1}^{2}}{r_{2}^{2}} = \left( \frac{1}{2} \right)^{2} = \frac{1}{4}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.