Q. The spectrum of a black body at two temperatures $27℃$ and $327℃$ is shown in the figure. Let $A_{1}$ and $A_{2}$ be the areas under the two curves respectively. The value of $\frac{A_{2}}{A_{1}}$ is

A) 1 : 16
B) 4 : 1
C) 2 : 1
D) 16 : 1
Explanation

(d) Area under given curve represents emissive power and emissive power $\propto T^{4} \Rightarrow A \propto T^{4}$
$\Rightarrow \frac{A_{2}}{A_{1}} = \frac{T_{2}^{4}}{T_{1}^{4}} = \frac{(273 + 327)^{4}}{(273 + 27)^{4}} = \left( \frac{600}{300} \right)^{4} = \frac{16}{1}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.