A plane monochromatic light wave of intensity Io falls normally on an opaque screen with a long slit having a semicircular cut on one side (Fig. 5.24). The edge of the cut coincides with the boundary line of the first Fresnel zone for the observation point P. The width of the slit measures 0.90 of the radius of the cut. Using Fig. 5.19, find the intensity of light at the point P.