Problem 5.69

In Lloyd's mirror experiment (Fig. 5.13) a light wave emitted directly by the source \(S\) (narrow slit) interferes with the wave reflected from a mirror \(M .\) As a result, an interference fringe pattern is formed on the screen \(S c\). The source and the mirror are separated by a distance \(l=100 \mathrm{~cm} .\) At a certain position of the source the fringe width on the screen was equal to \(\Delta x=0.25 \mathrm{~mm},\) and after the source was moved away from the mirror plane by \(\Delta h=0.60 \mathrm{~mm},\) the fringe width decreased \(\eta=1.5\) times. Find the wavelength of light.