Suppose white light falls on a double slit but one slit is covered by a violet filter (allowing λ = 400 nm). Describe the nature of the fringe pattern observed.

Question

Philoid · Accepted Answer

Here, we are using a white light which is made of seven colors including violet(VIBGYOR). when we use a violet filter, it means that only violet light of wavelength 400nm is allowed to pass. This light will only interfere with the violet of white light from the other slit giving us a prominent violet colored maxima. As other wavelengths do not undergo such interference, the minima wouldn’t be completely dark and would be formed by these wavelengths.