Question

a red colour passes from air to a medium having a velocity of red light two third that in air. what is the wavelengt of light in that medium ​

Answer 1

Given:

A red colour passes from air to a medium having a velocity of red light two third that in air.

To find:

Wavelength of light in that medium.

Calculation:

During refraction of light from one medium to another medium , the frequency of the electromagnetic wave (i.e. light) remains same.

Let initial wavelength be $\lambda$.

$\rm{\therefore \: frequency = constant}$

$\rm{= > \dfrac{v1}{ \lambda1} = \dfrac{v2}{ \lambda2} }$

$\rm{= > \dfrac{v}{ \lambda1} = \dfrac{ (\frac{2v}{3} )}{ \lambda2} }$

$\rm{= > \dfrac{v}{ \lambda} = \dfrac{ (\frac{2v}{3} )}{ \lambda2} }$

$\rm{= > \dfrac{1}{ \lambda} = \dfrac{ 2}{ 3(\lambda2} )}$

$= > \: \lambda2 = \dfrac{2 \lambda}{3}$

So , final answer is:

$\boxed{ \sf{ \large{ \: \lambda2 = \dfrac{2 \lambda}{3} }}}$