School of Physics Lecture Demonstration Manual

Hc-7 Ignition by Focusing Light

Published: Monday 13 March 2006 - Updated: Monday 28 March 2011


To demonstrate the focussing of infra red light and the resultant temperature rise.



Click on pictures to enlarge.

Ignition Pic 3

Ignition Pic 2

Ignition Pic 1


The Light globe is placed at the focus of one of the parabolic mirrors, so that a parallel beam of light is produced. The other mirror is placed approximately 2-3 meters in line to refocus the beam. The flammable pellet is accurately placed at the focus and will ignite within 10- 15 seconds.

Safety notes

Electrical safety 

Fire/Burn Safety 


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