A star (P) behaves like a perfectly black body emitting radiant energy at temperature ' T '. Another star (Q) also behaves like perfectly black body emitting radiant energy at temperature ' T / 4 ' and has radius eight times the radius of star ( P ) . The ratio of radiant energy emitted by ( P ) to that by ( Q ) is

Step-by-step solution

Concept: According to the Stefan-Boltzmann law energy radiated per unit area (j) j = T ^4 Where is the proportionality constant and T is temperature radiant energy E=j A , where A is the surface black body. Given, For ( a ) blackbody P , radius = R and temperature = T (b) blackbody Q , radius =8 R and temperature = T 4 E_ P E _ Q = T ^4 4 R ^2 ( T 4 )^4 4 (8 R )^2 = 4^4 8^2 = (8)^2 8^2 =1