One method of prodocing two in - phase point sources of light for interference is to form two images of a point source by means of the two halves of a lens,which has been split along a diameter[Fig.6.17].

A screen placed perpendicular tot he principal axis and 80 cm from the mage sources.What is the width of central maxima formed on the screen,if the wavelength of the light used is `5.4 xx 10^(-5) cm`?