Figure 5.14 illustrates the interference experiment with Fresnel mirrors. The angle between the mirrors is the distances from the mirrors' intersection line to the narrow slit and the screen are equal to and respec tively. The wavelength of light is Find: (a) the width of a fringe on the screen and the number of possible maxima; (b) the shift of the interference pattern on the screen when the slit is displaced by along the arc of radius with centre at the point ; (c) at what maximum width of the slit the interference fringes on the screen are still observed sufficiently sharp.