Navjyot Kalra
Last Activity: 10 Years ago
Sol. E → Energy radiated per unit area per unit time
Rate of heat flow → Energy radiated
(a) Per time = E × A
So, E base AI = eσT^4 * A/eσT^4 * A = 4πr^2/4π(2r)^2 = 1/4 ∴ 1 : 4
(b) Emissivity of both are same
= m base 1S base 1dT base 1/m base 2S base 2dT base 2 = 1
⇒ dT base 1/dT base 2 = m base S base 2/m base 1S base 1 = s base 14πr base 1^3 * S base 2/s base 24πr base 2^3 * S base 1 = 1 * π * 900/3.4 * 8π * 390 = 1 : 2 : 9