Light from a sodium lamp (wavelength 5890A˚) and a green laser (wavelength 5400A˚) are used separately, one after the other, in the same Young’s double–slit set-up. The slit separation is 0.25mm and the screen is 1.2m away from the slits.
(a) Find the fringe width when the sodium light is used.
(b) Find the fringe width when the green laser is used.
(c) Calculate the distance between the third bright fringe of the sodium pattern and the third bright fringe of the green pattern, measured from the respective central maxima.