Apparatus
- 1meter of 30swg constantan
- Voltmeter
- Amp meter
- Battery pack
- Variable resister
- Wires
Diagram
Preliminary Work
I tested the resistance of five different lengths of wire at 20cm intervals.
Results
This shows that my hypothesis was wrong so I investigated to find out why. I discovered that I had put the voltmeter in the wrong place in the circuit.
Plan
First I shall set up my experiment and then measure the resistance using an amp meter and a voltmeter for the following lengths of wire: 10cm
20cm
30cm
40cm
50cm
60cm
70cm
80cm
90cm
100cm
In order to keep my results reliable I shall keep the current the same through out the experiment, I will use the same piece of wire and keep the circuit set up the same.
To ensure safety for myself and others I shall make sure that equipment is used properly and that the wires are not in a position to trip people.
Results
Conclusion
The pattern shown by my graph shows that resistance does increase as the length of the wire increases. The graph shows that the resistance is directly proportional to the length of wire. The resistance is effect in this way because the electrons have more atoms to collide with so more energy is used travelling down a longer piece of wire.
This agrees with my original prediction.
Evaluation
I took my results using the same apparatus and made sure the wire was the correct length. I made sure the results were reliable by taking them twice. I think my results were good enough for me to draw an accurate conclusion from.
The investigation would have been better if the power source was constant, using a battery pack means that the current could decrease through out the investigation as the batteries wear out. To get better results I would use a bigger range of wire lengths.
