Find the angles of the first three principal maxima above the central fringe when this grating is illuminated with 672 nm light.

Complete Question

A grating has 767 lines per centimetre.Find the angles of the first three principal maxima above the central fringe when this grating is illuminated with 672 nm light.

The  first is  

 The second is  

 The third is  

Explanation:

From the question we are told that

        The  number of lines per cm is  

        The  wavelength is  

Generally the condition for constructive  interference is  

Here d is the distance of separation of the slit which is mathematically represented as

So          

For the  first angle  n =  1  

  So  

For  the second angle  n  =  2

      So  

For  the second angle  n  =  3

      So  

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