A ray travelling inside glass strikes a glass–air boundary at an angle of incidence of

PHYSICS · Single correct · A Level · Physics · Waves · Waves

Problem

A ray travelling inside glass

(n = 1.52)

strikes a glass–air boundary at an angle of incidence of

50^{\circ}

. What happens to the ray at the boundary? (a) It refracts into air, bending away from the normal, because

i=50^{\circ}

is less than the critical angle. (b) It partially reflects and partially refracts since

i=50^{\circ}

equals the critical angle. (c) It undergoes total internal reflection because

i=50^{\circ}

exceeds the critical angle of

\approx 41^{\circ}

. (d) It refracts into air, bending away from the normal, because

i=50^{\circ}

is greater than the critical angle.