Question

Assertion (A) : Black body is an ideal body that emits and absorbs radiations of all frequencies Reason (R) : The frequency of radiation emitted by a body goes from a lower frequency to higher frequency with an increase in temperature

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is not the correct explanation of A
• C. A is true but R is false
• D. Both A and R are false

Answer 1

Answer: (B)

Both A and R are true but R is not the correct explanation of A

Answer 2

Assertion (A) is true because a black body is defined as an ideal object that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. It is also an ideal emitter, emitting radiation according to its temperature. Reason (R) is also true; as the temperature of a black body increases, the peak of the emitted radiation spectrum shifts towards higher frequencies (shorter wavelengths), as described by Wien's displacement law. However, Reason (R) does not explain why a black body emits and absorbs radiations of all frequencies. The reason describes a consequence of temperature on the emitted spectrum, not the fundamental property of a black body's ability to interact with all frequencies. Therefore, R is true but not the correct explanation of A.