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Thermistor.
What is a Thermistor?
A thermistor is a component
whose
resistance changes
when its temperature changes.
A thermistor is a special
type of resistor whose
resistance decreases as its
temperature increases.
A plot of
resistance against temperature for
a
thermistor
is shown above. The plot is unusual
because it shows that a bigger current will flow
at a
higher temperature. For most components,
the
resistance increases as the
temperature increases
and a smaller current
flows at a higher temperature.
A plot of current against
voltage
is shown below.
The curve shows that it does
not obey ohm's
law.
What is a Thermistor
used for?
A thermistor can be used in a circuit to detect a
temperature change. For example, a thermistor
may
be used to keep a
freezer at the right temperature.
A circuit with a thermistor in it can switch the
freezer on
if the
temperature gets
too
high and switch the freezer
off again
when the correct low temperature is reached.
A thermistor can also be used to trigger a fire alarm.
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