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

Answer

A

Explanation

According to Kirchoff's law `(e_(lambda))/(a_(lambda)) = E_(lambda)`
If for a partical wave length `E_(lambda) = 1 rArr e_(lambda) = a_(lambda)`, ie., absorptivity of a body is equal to its emissivity. This statement also revels that a good radiator is also a good absorber and vice versa.