Physics 201- Introduction to Electricity & Magnetism
August 30- Coulomb's Law

 

 

 

 
 

 

 
Why do Wintergreen Lifesavers produce sparks when you chew them?

 
(image from Fundamentals of Physics by Halliday & Resnick)

 
 
 
 
 

When the sugar crystals in the candy rupture, one part of each ruptured crystal has an excess of electrons while the other parts have an excess of positive ions.  Almost immediately, electrons and ions jump across the gap of the rupture to neutralize the sides.  During the jumps, the electrons and positive ions collide with nitrogen molecules in the air.  The collisions cause the nitrogen to emit ultraviolet light that you cannot see and blue light that is too dim to see.  Oil of wintergreen in the crystals absorbs the ultraviolet light and immediately emits enough blue light to light up a mouth or pair of pliers.  However, if the candy is wet with saliva, the demonstration fails, because the conducting saliva neutralizes the two parts of the fractured crystal before the sparking can occur.
 
 

 

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Jeff Phillips
phillips@lmu.edu
Loyola Marymount University
Fall 2002