Reflecting a ray of light and a rubber ball
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
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.
a 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.
Catch the ray with a piece of plane mirror held in the hand and reflect it across the screen.
b Bounce the rubber ball against a hard wall or floor to show its reflection.
1 This demonstration introduces the idea of reflection. It is not intended for careful measurements, but students should see some connection between the angles.
2 Make sure that students observe the similarity between the path of the ray of light, and the path of the ball.
3 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-checked in August 2006