Question

As the number of slits of a diffraction grating increases, the bright fringes observed on the viewing screen __________.

(A) decrease in number
(B) increase in number
(C) get narrower
(D) get wider

Answer 1

Get narrower

Step-by-step explanation:

The equation of diffraction grating is given by :

`d\ sin\theta=m\lambda`

Where

d is the slit width

m is the order

Also,
`d=(1)/(N)`

N is the number of slits of a diffraction grating

As the number of slits of a diffraction grating increases, the bright fringes observed on the viewing screen get narrower. Also, the intensity of fringe will increase. So, the correct option is (c).