Question

Assertion :When an iorn rod is heated in a furnace, the radiation emmited 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. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

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:

$E=h\nu$

where $E$=energy, $\nu$=frequency and $h$=constant

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