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Light and the Electromagnetic Spectrum

Reflection, refraction and total internal reflection

  • 3 things to know
  • Paper 1

Overview

The law of reflection and the normal, refraction through a glass block, total internal reflection, its two conditions and the critical angle, optical fibres, and specular and diffuse reflection from mirrors, paper and wet roads.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

Compare specular and diffuse reflection, explain why a wet road dazzles at night, and name two surfaces reflecting specularly.

Key term

State the law of reflection.

Key term

A ray strikes a plane mirror at 30° to the normal. State the angle of reflection.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    State the law of reflection.

    Model answer

    The angle of incidence is equal to the angle of reflection.

  2. 2

    State the line from which the angle of incidence and the angle of reflection at a mirror are measured.

    Model answer

    Both are measured from the normal, drawn at right angles to the mirror surface.

  3. 3

    A ray strikes a plane mirror at 30° to the normal. State the angle of reflection.

    Model answer

    The angle of reflection is 30°, because it equals the angle of incidence.

  4. 4

    Describe what happens to a ray of light entering a glass block at an angle to the normal.

    Model answer

    It refracts at the surface and bends towards the normal as it enters the glass.

  5. 5

    Describe the path of the ray leaving a rectangular glass block, compared with the ray that entered it.

    Model answer

    It travels parallel to the ray that entered but is shifted sideways.

  6. 6

    Define total internal reflection.

    Model answer

    Total internal reflection is when light meeting a boundary from inside the denser material is entirely reflected back and none escapes.

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