Investigate the relationship between temperature and resistance in a thermistor.
Extracts from this document...
Introduction
Thermistors Investigation
Aim
To investigate the relationship between temperature and resistance in a thermistor.
Introduction
A current is the flow of charge round a circuit, this can be in the form of ions in a liquid or electrons in a metal.
Resistance is anything that slows the flow of electrons round the circuit.
Ohm's law states that the voltage is equal to the current multiplied by the resistance - V=IR
This can be re-arranged to say R=V/I.
Ohms law states that in a metal component the ratio of voltage to current remain constant, meaning that the resistance stays the same as long as the temperature remains the same. In this experiment I will be changing the temperature therefore this rule will not apply, however the equation R=V/I is always true as it is the way resistance is defined.
In a wire when the temperature is increased the resistance increases. This is because at a higher temperature the lattice atoms are vibrating faster and are colliding with the electrical current and slowing down the flow of charge.
This is also true in a thermistor but there is another competing effect because it is a semiconductor. Being a semiconductor means that the outer electrons are not free at room temperature but when heated the get more energy and are freed. This means that there are more electrons available to conduct.
Middle
Experiment Diagram
Results
Temperature (0C) | Current (A) | Voltage (V) | Resistance (Ohms) | Average Resistance (Ohms) | ||||||
Trial 1 | Trial 2 | Trial 3 | Trial 1 | Trial 2 |
Conclusion
I would also like to try lower temperatures to see if there was a minimum energy needed to free the electrons if so the graph would be-
This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.
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