How is the wavelength of monochromatic light measured

[franklinear]

how is the wavelength of monochromatic light measured by using diffraction grating and spectometer?

 

[Dadface]

What have you found out so far?

 

[franklinear]

Using diffraction grating, when incident parallel beam is at normal incidence, then emergent parallel beams are seen in directions such that
dsinθ = nλ

by considering the spacing of grating, and the order of the diffracted beams as well as the angle of diffracted beams to the normal, the wavelength may be measured.

Is it Correct?

What about spectrometer?

 

[Dadface]

Hello franklinear,yes it is correct.A spectrometer is an optical instrument that can be used to make measurements of the type you described with a high degree of accuracy.There is a collimator which can be adjusted to produce the parallel incident beam,a table on which to place the grating and a telescope which can be adjusted to focus the emergent beams.The table and telescope can be rotated and and there is a vernier scale to measure the angles.