Light is incident from glass ( = 1.5 ) into air. Determine the angle of incidence that results in an angle of deviation of 90^ .

Step-by-step solution

The critical angle for the glass-air interface is given by _c = 1 = 1 1.5 = 2 3 . For refraction, the angle of deviation is = r - i . If = 90^ , then r = 90^ + i , which is not possible since the maximum angle of refraction is 90^ . Therefore, the light must undergo total internal reflection. For total internal reflection, the angle of deviation is = 180^ - 2i . Given = 90^ , we have: 180^ - 2i = 90^ 2i = 90^ i = 45^ We must verify if this angle is greater than the critical angle. Since 45^ = 1 2 0.707 and _c = 2 3