Question

What is the wavelength of the light entering an interferometer if 402 bright fringes are counted when the movable mirror moves 0.115 mm?

Answer 1

Answer:

The  value is  $\lambda = 572 *10^{-9} \ m$

Explanation:

From the question we are told that

    The  number of  bright fringes is  n =  402

     The  displacement of the mirror is  $\delta l = 0.115 \ mm = 1.15 *10^{-4} \ m$

 

Generally the number of fringes is mathematically represented as

       $n = \frac{2 * \delta l }{\lambda }$

=>    $\lambda = \frac{2 * \delta l }{n }$

=>     $\lambda = \frac{2 * 1.15*10^{-4} }{402 }$

=>   $\lambda = 572 *10^{-9} \ m$