Question

The frequency of a wave of light is $12\times {10}^{14}{s}^{-1}$. The wave number associated with this light is

• A. $5\times {10}^{-7}m$
• B. $4\times {10}^{-8}c{m}^{-1}$
• C. $2\times {10}^{-7}{m}^{-1}$
• D. $4\times {10}^{4}c{m}^{-1}$

Answer 1

The correct option is D $4\times {10}^{4}c{m}^{-1}$

• We know that, $\lambda =\frac{c}{\nu }$
  

$\lambda =\frac{3\times {10}^8}{12\times {10}^{14}}=\frac{1}{4}\times {10}^{-6}m$

• Wave number $\left(\overline{\nu }\right)$ is the reciprocal of wavelength. That is, $\overline{\nu }=\frac{1}{\lambda }$

$\overline{\nu }=4\times {10}^6{m}^{-1}=4\times {10}^{4}c{m}^{-1}$