question_answer

Direction for: In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as

Assertion:  For higher temperatures the peak emission wavelength of a black body shifts to lower wavelengths. Reason: Peak emission wavelengths of a black body is proportional to the fourth-power of temperature.

A) If both assertion and reason are true and reason is the correct explanation of assertion.

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

C) If assertion is true but reason is false.

D) If both assertion and reason are false.

Correct Answer: C

Solution :

                Figure shows that how the energy of a black body radiation varies with temperature and wavelength. As the temperature of the black body increases, two distinct behaviors are observed. The first effect is that the peak of the distribution shifts to shorter wavelengths. This shift is found to obey the following relationship called Wiens displacement law. \[{{\lambda }_{m}}T=constant\] The second effect is that the amount of energy, the black body emits per unit area per unit time increases with fourth power of absolute temperature T.