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Light and sound

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Question 32

This question is about how light travels through different media.

A ray of light is directed inside a semi-cylindrical acrylic plastic block towards the center of its flat face, which is in contact with air.

a.

Under certain conditions, the ray of light does not exit the plastic block but is reflected entirely inside it. State the name of this process.

[1]
b.

If the angle of incidence of this ray at the plastic-air boundary is 48∘48^\circ48∘, state the angle of reflection.

[1]
c.

The direction of the incident ray is now changed so that the light passes out of the plastic block into the air. Describe how the direction of the ray changes as it crosses the boundary from plastic to air.

[1]
d.

State the name of this process.

[1]
e.

State the equation linking critical angle, ccc, and refractive index, nnn.

[1]
f.

The refractive index of the acrylic block is 1.491.491.49. Calculate the critical angle for the boundary between this plastic and air. Give your answer to three significant figures.

[2]
g.

The light source is adjusted so that the ray of light meets the plastic-air boundary at an angle of incidence of 45∘45^\circ45∘. Explain what happens to this ray of light.

[2]

Light and sound Questions

  1. IGCSE
  2. /Physics
  3. /Light and sound