Question

Two spheres of same material have radii $1$ m and $4$ m and temperatures $4000K$ and $2000K$ respectively. The ratio of energy radiated per second by the first sphere to that of second is :

• A. 1:1
• B. 16:1
• C. 4:1
• D. 1:9

Answer 1

The correct option is A 1:1

We know that radiation from the surface is given as $E=ϵ\sigma A{T}^4$

$E\propto r^2{T}^4$

$\frac{E_1}{E_2}=\frac{1\times {4000}^4}{16\times {2000}^4}=\frac{256}{256}=\frac{1}{1}$