Bimetal Strip Thermostat

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 Code Number :   4A30.11

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Reprinted by permission of Dick Berg, University of Maryland, for use on this website.

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Condition :   Good  
Principle :   Expansion & Contraction with Temperature Variation  
Area of Study :  Heat & Fluids   
Equipment :   Bimetal strip thermometer apparatus, grill lighter, distilled water.

Procedure :   Hold the grill lighter flame under the curved part of the thermostat.  After a few seconds the blue light should go out and the red light should come on.  Pour distilled water over the curved part of the thermostat and this should cool it down enough to make the blue light come on again.

This thermostat is the typical home thermostat with a mercury switch atop a bimetal coil.   Adjust the thermostat so that the lights are on at room temperature.  Heat the coil with the flame from a grill lighter, and the coil will expand turning the lights off.  Cool the coil with some water and the lights will go on again.  

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   References

H. Richard Crane,  "Popping Bimetal Can Keep You Warm or Cool,"  TPT, Vol. 36, # 5, p. 302, (May 1998).

 

H- 044:  "Thermostat - Auto - Stove - Bimetal,"  DICK and RAE Physics Demo Notebook.

 

C.L. Stong,  "An Electrometer, a Temperature Control Apparatus, and a Simple Electric Motor,"  The Amateur Scientist,  (October, 1965).



Mail Questions and Comments to:  Dale Stille