A right-angled isosceles glass prism has and

PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Geometric Optics · Geometric Optics

Problem

A right-angled isosceles glass prism

ABC

has

\angle A = 90^{\circ}

and

AB = AC

. The prism is placed in air. A monochromatic ray of light is incident normally on face

AB

. (Refractive index of glass =

1.52

.) (a) Calculate the critical angle for the glass–air interface. (b) Show that the ray meets face

BC

at an angle of incidence of

45^{\circ}

. (c) Decide, with calculation, whether the ray will undergo total internal reflection at face

BC

. If it does, trace its subsequent path and find the angle it makes with face

AC

on emerging from the prism. (d) Give one reason why such a prism is preferred to a plane mirror for turning a light beam through

90^{\circ}