Welcome to practical physicsPracticle physics - practical activities designed for use in the classroom with 11 to 19 year olds

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

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.


Apparatus set-up

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. 

Bouncing ball

Teaching notes

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


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