A lens of diameter 5.0 cm and focal length f = 25.0 cm was cut along the diameter into two identical halves. In the process, the layer of the lens a = 1.00 mm in thickness was lost. Then the halves were put together to form a composite lens. In this focal plane a narrow slit was placed, emitting monochromatic light with wavelength λ = 0.60μm. Behind the lens a screen was located at a distance b = 50 cm from it. Find:
(a) The width of a fringe on the screen and the number of possible maxima;
(b) The maximum width of the slit 5nax at which the fringes on the, screen will be still observed sufficiently sharp.