The student measures the distance s between the central maximum and the second order maximum on the screen.

The experiment is repeated for different wavelengths of light.

It is suggested that s and the wavelength λ are related by the equation

s^2
-----
s^2 + D^2 = 4N^2λ^2

where D is the distance between the diffraction grating and the screen and N is the number of lines per unit length of the diffraction grating.

(a) A graph is plotted of 1/s^2 on the y-axis against 1/λ^2 on the x-axis.

Determine expressions for the gradient and y-intercept.?