Star A has a radius twice that of Star B

PHYSICS · Single correct · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics

Problem

Star A has a radius twice that of Star B. The wavelengths at which their spectral emissions peak are

400\,\text{nm}

for A and

800\,\text{nm}

for B. Assuming both are perfect blackbodies, the ratio of their total luminous powers

P_A / P_B

is (a)

16

(b)

8

(c)

64

(d)

32