Reflection of light(Exposition)

Reflection from surfaces

Light beams are reflected from surfaces in a very particular way. The the angle of incidence is equal to the angle of reflection. This is called the law of reflection.

Instead of the beams you see you can draw lines to predict where the light will travel. These drawn lines are called rays.

Predicting what will happen using rays

This shows how an book makes a shadow, and how you can change the size of the shadow by moving the book or the wall. Draw such diagrams carefully and you can tell what will happen.

  • Show the light source as a point.
  • Draw two rays, as straight lines.
  • Use an arrow to show the ray leaving the source.
  • Use thick line to show the book.
  • Then the shadow is on the wall will be between where the two rays meet the screen.

    Drawing rays is a way of working out what will hapen. These drawings are not pictures of what you'll see.

    You can redraw the diagram to predict what will happen to the shadow.

  • Move the torch closer to the barrier (the shadow gets larger).
  • Move the screen away from the opaque barrier? (the shadow gets larger).

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