Question

Light of wavelength 510 nm is used to illuminate normally two glass plates 24.3 cm in length that touch at one end and are separated at the other by a wire of radius 0.023 mm. How many bright fringes appear along the total length of the plates.

Answer 1

Answer:

$m = 180 \ bright \ fringes$

Explanation:

From the question we are told that

    The  wavelength is  $\lambda = 510 \ nm = 510 *10^{-9} \ m$

    The length of the of the plate is  $l = 24.3 \ cm = 0.243 \ m$

    The radius of the wire  is $r= 0.023 \ mm = 2.3 *10^{-5} \ m$

Generally the diameter of the wire which is the distance between the glass  plates is mathematically represented as

             $d = 2 * r$

=>          $d = 2 * 2.3 *10^{-5}$

=>          $d = 4.6 *10^{-5} \ m$

 Generally the condition for constructive interference is mathematically represented as

           $2 *d = m \lambda$

=>        $m = \frac{2d}{\lambda}$

=>        $m = \frac{2 * (4.6* 10^{-5})}{ 510 *10^{-9} }$

=>        $m = 180 \ bright \ fringes$