A partially reflective square mirror is situated on the ry plane with its vertices at (-1, -1), (1, -1), (1, 1) and (-1, 1). Light of uniform intensity, travelling in the z direction hits the mirror. The fraction of incident light that is reflected at (x, y) is (x- y)?/4. What is the fraction of the power of light that is reflected? [Hint: Power of light = Jf (Light intensity) dA , where dA = dady is the area element