Question:

In an experiment of single slit diffraction pattern, first minimum for red light coincides with first maximum of some other wavelength. If wavelength of red light is 6000Ao, then wavelength of first maximum will be?

3000Ao

4000Ao

5000Ao

6000Ao

First Minima of red light coincides with maxima of some other light
(n+1/2)λunknown=nλred
λunknown=2/3×6000
λunknown=4000Ao