Reflection
Light, Sound and Waves

Reflecting a ray of light and a rubber ball

Practical Activity for 14-16 PRACTICAL PHYISCS

Demonstration

Comparing the paths of a reflected ray of light and a rubber ball.

Apparatus and Materials

  • Light source, compact (100 W 12 V)
  • L.T. variable voltage supply (12 V 8 A)
  • White screen (500 mm x 300 mm approx)
  • Card with slit (5 mm wide approx)
  • Retort stand and boss
  • Plane mirror
  • Rubber ball

Health & Safety and Technical Notes

Be aware that compact light sources using tungsten-halogen lamps without filters are significant sources of UV. Ensure that no-one can look directly at the lamp.

Read our standard health & safety guidance


Procedure

  1. Set up the compact light source with the card and slit in front of it, so that a thick ray of light splashes across the vertical white screen.
  2. Catch the ray with a piece of plane mirror held in the hand and reflect it across the screen.
  3. Bounce the rubber ball against a hard wall or floor to show its reflection.

Teaching Notes

  • This demonstration introduces the idea of reflection. It is not intended for careful measurements, but students should see some connection between the angles.
  • Make sure that students observe the similarity between the path of the ray of light, and the path of the ball.
  • You could ask the question 'What is light made of... bullets?'. If students have seen waves being reflected in a ripple tank, they might also give waves as an answer.

This experiment was safety-tested in August 2006

Reflection
is formalised by Law of Reflection
can be exhibited by Progressive Wave
has the special case Total Internal Reflection
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