Assertion: When an iron rod is heated in a furnace, the radiation emitted goes from a lower frequency to a higher frequency as the temperature increases. Reason: The energy of a quantum of radiation is proportional to its frequency.

Question

Assertion: When an iron rod is heated in a furnace, the radiation emitted goes from a lower frequency to a higher frequency as the temperature increases. Reason: The energy of a quantum of radiation is proportional to its frequency. (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.

Tardigrade Admin · Accepted Answer

According to Black-body radiation: At ambient temperature, the majority of the emitted spectrum is in the long wave infrared (short frequency) which is not visible. As the temperature rises, the spectrum shifts towards shorter wavelengths (higher frequency). At temperatures around

900 K

, part of the radiation becomes visible since wavelengths in the

700 nm

region are present and the object start to appear "red hot". Thus, when an iron rod is heated in a furnace, the radiation emitted goes from a lower frequency (high wavelength region) to a higher frequency (lower wavelength) as the temperature Increases.
According to Planck's relation we have:

E = h v

where

E =

energy,

v =

frequency and

h =

constant
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

Q. Assertion: When an iron rod is heated in a furnace, the radiation emitted goes from a lower frequency to a higher frequency as the temperature increases. Reason : The energy of a quantum of radiation is proportional to its frequency.

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

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

If assertion is true but reason is false.

If both assertion and reason are false.

Q. Assertion: When an iron rod is heated in a furnace, the radiation emitted goes from a lower frequency to a higher frequency as the temperature increases.
Reason : The energy of a quantum of radiation is proportional to its frequency.