12th Class Physics EM Waves Question Bank MCQs - Electromagnetic Waves

One requires \[11\text{ }eV\] of energy to dissociate a carbon monoxide molecule into carbon and oxygen atoms. The minimum frequency of the appropriate electromagnetic radiation to achieve the dissociation lies in

A) Visible region

B) Infrared region

C) Ultraviolet region

D) Microwave region

Correct Answer: C

Solution :

Option [c] is correct.

Explanation: \[\operatorname{E}=11\ eV=11\times 1.6\times 1{{0}^{-19}}J\]

\[h=6.62\times {{10}^{-34}}Js\] \[E=hv\]

\[\operatorname{v}=\frac{E}{h}=\frac{11\times 1.6\times {{10}^{-19}}}{6.62\times {{10}^{-34}}}=\frac{8.8\times {{10}^{-19+34}}}{3.31}\]

=\[\frac{800}{331}\times {{10}^{15}}\operatorname{Hz}=2.65\times {{10}^{15}}\operatorname{Hz}\]

This frequency radiation belongs to the ultraviolet region.