Question

The spacing between the slits of a diffraction grating is 1600 nm (1 nm = 10-9 m). How many lines per mm does this grating have?

Answer 1

Explanation:

It is given that,

Slit spacing, $d=1600\ nm=1600\times 10^{-9}\ m$

We need to find the lines per mm in the grating. The relation between the slit spacing and number of lines is given by :

$N=\dfrac{1}{d}$

$N=\dfrac{1}{1600\times 10^{-9}}$

N = 625000 m

or

So, number of lines per mm is 625. Hence, this is the required solution.