Answer to Question #261364 in Optics for Kiso

Question

A prism spectrometer is set up with white light source. For a certain positions of the telescope and prism,the image is white and for other positions the image is coloured .Explain

Answer 1

When the white light passes through the prism, it is dispersed into a spectrum of colors as the angle of diffraction is dependent on the refraction and wavelength of different colors. As a result, these colors form interference pattern with each other and is observed through the telescope. If the colors perfectly superimpose with zero path difference, we observe a white light.

If there is a path difference with conditions of maxima being fulfilled along with, we observe different colors of the spectrum through the telescope. However, the position of the colors from the white light is dependent on the wavelength. Thus with at different positions (or angles) we observe different colors or white light depending on the path difference between interfering wavelengths.