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Investigation into the relationship of the length of wire and the resistance.

Extracts from this document...

Introduction

Thomas Hone20/01/04

Investigation into the relationship of the length

of wire and the resistance

How does the length of wire affect the resistance?

Planning

Prediction: I think that the longer the piece of wire, the more resistance will be created. I think this because in a circuit electrons move around it creating electricity in the wires. If there is more length of wire there will be then more wire atoms in the way of the electrons moving round the circuit:

- Wire Atom

- Electron

Small piece of Wire: There some atoms in

way of the electrons moving.

Long piece of wire: There are a lot morewire atoms in the way of electrons.

Resistance is caused when electrons collide with atoms. Because there is a lot more wire atoms in the way of the electrons, the electrons must collide more, so slow down. E.g. if you are travelling down a road and there are a few of parked cars, it will take you a while to get through, but if you are travelling down a longer piece of road and there are more parked cars it will take you much longer.

As the electrons slow, thus the current, (current = how fast the flow of electrons is) slows down.

Preliminary Work:

Middle

Work out the resistance (R) by V divided by I.

I= current     V= Voltage = 0.9 volts.

Fair test: These things I must always keep the same to ensure the test is fair and that there is a minimal chance of error as possible:

• Have the same piece of wire each time as different wire could vary slightly or have different properties, so give different results.
• Keep the same voltage throughout the experiment.
• Have the same equipment – wires, voltmeters, ammeters, power supply. – If changed these could give different readings.
• Have the wire measured by the same ruler and person – If someone else does it with a different ruler they could measure it differently or off slightly.

Obtaining Evidence

Results table:

 Length of wire 1st Test 2nd Test 3rd Test Average resistance V I R V I R V I R 10cm 0.9volts 0.8Amps 1.125Ohms 0.9Volts 0.86Amps 1.047Ohms 0.9Volts 0.8Amps 1.125Ohms 1.098Ohms 20cm 0.9Volts 0.44Amps 2.045Ohms 0.9Volts 0.44Amps 2.045

Conclusion

I am quite happy with out results because they are good results. The results may have been wrong, but this would be quite unlikely as we have a strong correlation. Also I think that we have enough information to draw conclusions as they show good connection.

Another improvement would also be to change the equipment. It could more precise or have newer ones which wouldn’t have been damaged or altered. Things such as the crocodile clips where hard to position very accurately so I would look for alternatives. The room could have also affected the results. As the day went on it got warmer, so affecting the temperature of the wire. If I wanted to be extremely precise and accurate in future experiments I could do the experiment in a temperature controlled room.

I think the conclusions I have drawn are good. I have strong evidence to base them on and there is good evidence. The errors could have been small mistakes from the equipment. If I did another experiment into this area I would try to do things such as

- The thickness of the wire

- Which type of wire

- The temperature of the wire.

-  -

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