Question

If the sun were to increase in temperature from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on earth to what it was previously, will be ___________

(a) 4

(b) 16

(c) 32

(d) 64

This question was addressed to me during an online exam.

This is a very interesting question from Thermal Expansion in division Thermal Properties of Matter of Engineering Physics I

Answer 1

Correct option is (d) 64

Best explanation: Energy radiated by the sun per second,

E = σAT^4= σ×4πR^2×T^4

When its radius and temperature change to 2R and 2T respectively,

E^‘=σ×4π(2R)^2×(2T)^4

E^‘/E=64.