Edexcel A-Level Physics AS 2.3.46 Critical Angle Questions

Practise Edexcel IAL Physics 2.3.46 by calculating critical angles at material boundaries, deriving refractive-index ranges from measured angles and identifying the limiting ray in diagrams.

Exam points

calculate critical angle from refractive-index ratios at glass, water or core-cladding boundaries
use measured critical angle and uncertainty to find possible refractive-index ranges
identify the critical angle from a boundary diagram using the normal and limiting ray

[Maximum number: 5]

A student determined the refractive index of a transparent material. The student had a semicircular block of the material as shown.

Figure for Question Edexcel A-Level Physics AS 2.3.46 Critical Angle Questions question 1 — Edexcel A-Level Physics AS

(a)

Complete the diagram to show the critical angle.

[ 1 ]

(b)

Determine the refractive index of the transparent material, using measurements from the diagram.

Refractive index =

[ 2 ]

(c)

The student repeated the process for a second semicircular block of a different transparent material. Her measured critical angle was $C=41.0^\circ\pm0.5^\circ$ . Calculate the range of possible refractive-index values.

[ 2 ]

Use $n=1/\sin C$ at the limiting angles. For $C=40.5^\circ$ , n=1.54;
for $C=41.5^\circ$ , n=1.51. Thus the possible range is approximately 1.51 to 1.54.

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Edexcel A-Level Physics AS 2.3.46 Critical Angle Questions question 1

Question (a)

Question (b)

Question (c)