Assertion : A body that is a good radiator is also a good absorber of radiation at a given wavelength.
Reason : According to Kirchhoff's law the absorptivity of a body is equal to its emissivity at a given wavelength

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If the assertion and reason both are false.

Answer

A

Explanation

According to Kirchhoff’s law `(e_(lambda))/(a_(lambda))=E_(lambda)`
If for a particular wave length `E_(lambda)=1 implies e_(lambda)=a_(lambda)` i.e., aborptivity of a body is equal to it’s emissivity. This statement also reveals that a good radiator is also a good absorber and vice versa.