How can diffraction gratings be used to measure the wavelengths of light accurately?

Question

Or to measure small distances?

Answer 1

It is most easily done using a spectrometer.
This instrument rotates the receiving slit at twice the rate of the diffracting element (prism or grating) and makes the finding of the deviation maximum a simple matter.

You then need to use the standard diffraction formula to calculate the wavelength. (assuming you are given the lines per mm of the grating - or have counted them)

Answer 2

unlikely for severe priced equipments.....attempt out measuring that's frequency while that's chop up into factors and then degree the wavelength applying c=vf.the place c is the value of sunshine,v the frequency and f the wavelength