Resistance Experiment

A series of free GCSE/IGCSE Physics Notes and Lessons.

Resistance Experiment
In this lesson, we will describe how to investigate the factors affecting the resistance of electrical circuits.

How the resistance of electrical circuits is affected by the length of a wire at constant temperature?

Required practical: Resistance
The resistance of the wire is directly proportional to the length.

A zero error is a reading on a measuring instrument when the value should be zero. This is a systematic error. We cannot reduce it by carrying out repeats. In the case of resistance, we need to subtract the zero error from all of our readings. There is also some resistance caused by the contact between the crocodile clip and the wire.

If the temperature of the wire increases, then the resistance will also increase. Some of the precautions to take:

• Use a low potential difference. This will keep the current low, reducing any heating in the wire.
• Only turn on the current when taking a reading. Turn of the current between readings.

Resistance vs Length Of Wire - GCSE Science Required Practical
Experiment to show how to measure the resistance of a wire when you change its length.

• set up a circuit which can measure the potential difference and current across a wire at different lengths along the wire
• calculate the resistance for different lengths of wire and state the relationship between resistance and length.

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