WOLFRAM|DEMONSTRATIONS PROJECT

Bimetallic Spiral Thermometer

​
bimetal spiral components
active
Mg
Al
Ag
Cu
passive
Ti
Fe
Ni
Au
strip thickness
0.2
outside temperature (°C)
20
auto-calibrate
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
L
and strip thickness
s
is given by
ϕ=(
α
1
-
α
2
)(T-
T
0
)L/s
, where
α
1
and
α
2
are the coefficients of linear expansion of the component materials used.