A clear plastic paperweight with an unknown index of refraction rests on your desk as shown in the figure. A ray of light enters the top of the paper weight with a 55° angle of incidence and undergoes total internal reflection at the side. (a) Determine the minimum value for the index of refraction of the plastic for which this will occur. (b) If the angle of incidence as the light enters the paper weight is increased, is the minimum value for the index of refraction increased or decreased?

A clear plastic paperweight with an unknown index of refraction rests on your desk as shown in the figure. A ray of light enters the top of the paper weight with a 55° angle of incidence and undergoes total internal reflection at the side. (a) Determine the minimum value for the index of refraction of the plastic for which this will occur. (b) If the angle of incidence as the light enters the paper weight is increased, is the minimum value for the index of refraction increased or decreased?