Question

Explain how you would find the specific wavelength of a light source using a diffraction grating?

Answer 1

Step-by-step explanation:

Using diffraction grating

Considering the expression:

`d* sin\theta=m* \lambda`

Where, m = 1, 2, .....

d is the distance between the slits.

The formula can be written as:

`sin\theta=\frac {\lambda}{d}* m` ....1

The location of the bright fringe is determined by :

`y=L* tan\theta`

Where, L is the distance between the slit and the screen.

For small angle ,
`sin\theta=tan\theta`

So,

Formula becomes:

`y=L* sin\theta`

Using 1, we get:

`y=L* \frac {\lambda}{d}* m`

By finding the distance between the first fringe (m = 1) fringe and the central maximum (y) , wavelength can be calculated as the distance between slit and scree (L) and the distance between the slits (d) are known in an experiment.