Bimetallic Spiral Thermometer
Bimetallic Spiral Thermometer
This Demonstration simulates a classical bimetallic spiral thermometer (dial or coil thermometer).
An Archimedes's spiral made of a coiled bimetal strip gives a deflection proportional to the surrounding temperature and can serve as a thermometer.
The angular deflection of a bimetal spiral of length and strip thickness is given by , where and are the coefficients of linear expansion of the component materials used.
L
s
ϕ=(-)(T-)L/s
α
1
α
2
T
0
α
1
α
2