IB Physics HL C 3 4 Total Internal Reflection Questions

Practise IB Physics HL C.3.4 by solving critical-angle and fibre-acceptance problems and tracing rays across multiple optical boundaries.

Exam points

Solve multi-boundary critical-angle problems with sin θc = n₂/n₁ and explicit incidence checks.
Determine fibre acceptance angles from core–cladding and air–core refraction.
Trace prism or fibre rays and justify total internal reflection when no refracted ray exists.

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Study C.3.4—Total internal reflection conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

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Monochromatic light enters the base of a plastic beaker that contains water with an oil layer floating on it. A student draws a diagram to show the directions the light takes as it passes through the layers. The student's diagram has one error at position A and one error at position B. The refractive indices of the materials are shown on the diagram.

Figure for Question IB Physics HL C 3 4 Total Internal Reflection Questions question 1 — IB Physics HL

The light is refracted at an angle of $32^{\circ}$ when it enters the plastic layer as shown.

Calculate the critical angle for the plastic-water interface.

$\begin{aligned} \frac{\sin i}{\sin r}=\frac{1.33}{1.60} \text { and } \sin r=1 i=\text { «sin }{ }^{-1} 0.831 »=56 \text { " }^{\circ} \text { » } \end{aligned}$

Accept 0.98 rad (unit required)

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IB Physics HL C 3 4 Total Internal Reflection Questions question 1