Question

A the black body spectrum of an object is such that its radiant intensity (i.E. Intensity per unit wavelength interval) is maximum at wavelength of 200 nm. Another object , has the maximum radiant intensity al 600 nm. The ratio of power emitted per unit area by source to that of source is (a) 1: 81 (b) 1:9 (c) 9:1 (d) 81:1

Answer 1

Answer:

Explanation:

E1:E2 =81:1

Answer 2

answer : option (d) 81 : 1

explanation : The power emitted per unit area by source is given by using Stefan's law and Wien's displacement law.

according to Stefan's law,

power emitted per unit area is directly proportional to T⁴ , where T is temperature of source.

and according to Wien's displacement law, Temperature is directly proportional to wavelength.

so, power emitted per unit area is inversely proportional to (wavelength)⁴

or, $\frac{P_1}{P_2}=\frac{\lambda_2^4}{\lambda_1^4}$

= (600nm)⁴/(200nm)⁴

= (3/1)⁴

= 81/1

hence, option (d) is correct choice.