The aim for this experiment is to find how a thermistor works and how temperature affects the resistance of current in the circuit.

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Thermistors have many different uses, they can be used to protect the filaments of a projector lamp and T.V. tubes from current surges as they are switched on, they can also be used for fire and frost alarms.

Resistance shows how much current is flowing through, and how fast the current flow is. The greater the resistance, the more potential difference is needed to push a current through a wire. The resistance can be calculated by:

Resistance (R) =  Potential difference across the wire (V)

                   Current through the wire (I)

There can be many factors, which affects the resistance, some variables, which can affect my results, are:

Temperature- this can affect the resistance of the thermistor; it lowers the resistance and so allows more electrons to pass through.

Length and thickness of wire- increasing the length of wire will increase the resistance, as there will be a longer distance for the current to travel. The thicker the wire, the lower the resistance, this is because there would be more space for the electrons to pass through. To control this, will use the same wires each time I do the experiment.

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Potential difference or voltage- increasing the potential difference will increase the power of the current, so the electrons will move faster through the circuit. Potential difference is measured in voltage using a voltmeter.  To control this I will keep it constant by using a voltmeter and make it has the same reading each time.

To find the rate at which the resistance of the thermistor decreases, I will find the gradient for my results. The gradient will show how fast or slow the rate of resistance falls. I will use the gradient formula:

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