Fig. 5.1 shows a glass block ABCD with refractive index 1.5. It has one curved face AB and three straight faces, BC, CD and DA, with right angles at C and D. The curved face AB is a quarter of the circumference of a circle centred at P. A ray of monochromatic light passes into the block through the curved face AB and meets side BC at P. Part of the light is transmitted into the air and part is reflected.
(a)[1]
State the meaning of monochromatic.
(b)[2]
Explain why the ray of light keeps the same direction as it enters the block through side AB.
(c)[2]
Show that the critical angle $c$ for glass with refractive index 1.5 is $42^\circ$.
(d(i))[2]
State and explain what happens to the light when it reaches P.
(d(ii))[1]
Describe what occurs when this reflected light reaches side CD.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Light/electromagnetic radiation with a single frequency” …