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# Thermistors and p.d Watch

1. Could anyone help i don't understand what happens to the p.d across a thermistor as its temperature increases.

I understand the resistance decreases and that the current increases but how do you explain the p.d across it. Does the current increase at a lower rate then the resistance decreases?

How would you explain how the p.d changes as the temperature of the thermistor increases?

This is for an NTC thermistor in a potential divider circuit
2. (Original post by thebearissquare)
Could anyone help i don't understand what happens to the p.d across a thermistor as its temperature increases.

I understand the resistance decreases and that the current increases but how do you explain the p.d across it. Does the current increase at a lower rate then the resistance decreases?
in a potential divider the current depends on the resistance of the series resistors added together, if one of the resistors is lowering in value (i.e. a thermistor) the current has to increase and the proportion of the total pd appearing across the thermistor decreases ... but the effect on the output of the circuit will depend on the component values.

e.g. if you've got a thermistor that starts at 1k ohm and goes down to 500 ohm it's not going to make a dramatic difference to the output if it's in series with a 1M ohm fixed resistor... you'd be trying to measure a change of roughly 1/1000 th of the input voltage.

if the resistances are more similar it works out differently

How would you explain how the p.d changes as the temperature of the thermistor increases?

This is for an NTC thermistor in a potential divider circuit

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