Explanation:
Using diffraction grating
Considering the expression:
[tex]d\times sin\theta=m\times \lambda[/tex]
Where, m = 1, 2, .....
d is the distance between the slits.
The formula can be written as:
[tex]sin\theta=\frac {\lambda}{d}\times m[/tex] ....1
The location of the bright fringe is determined by :
[tex]y=L\times tan\theta[/tex]
Where, L is the distance between the slit and the screen.
For small angle , [tex]sin\theta=tan\theta[/tex]
So,
Formula becomes:
[tex]y=L\times sin\theta[/tex]
Using 1, we get:
[tex]y=L\times \frac {\lambda}{d}\times m[/tex]
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.
