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What affects the resistance of a metal wire?

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Introduction

What affects the resistance of a metal wire?

Physics for you, Keith Johnson, and Physics revision guide by Richard Parsons.

Plan

4 factors that affect resistance

· As the length of the wire increases, the resistance also increases.

· As the cross sectional area increases, the resistance decreases.

· Copper is a good conductor and is used for connecting wires, as different wires have different resistances this could be investigated.

· As the temperature increases, the resistance of a wire increases.

The factor that I am going to investigate is the length of the wire. I will constantly increase the length by 10cm starting at 10cm and ending at 100cm. Current is the flow of electrons around a circuit. For an electric current to flow, there must be no gaps in the circuit. Electrons flow from atom to atom round from the negative pole to the positive.

I predict that when I double the wire's length, the resistance will double. This means that when the electrons travel along the wire they are constantly

...read more.

Middle

2. The type of metal being used, I will make sure that only copper wire is being used.

3. The temperature of the wire-I will keep the current the same, this will ensure that the wire does not overheat. I will take 3 readings from each of the lengths and then use the average to put into my results table.. Resistance will be calculated by voltage/current. I will make sure that the wire or any other component gets too hot by keeping safe levels of current.

Results

Length (cm)

Voltage (Volts)

Current (Amps)

Resistance (W)

10

20

30

40

50

60

70

80

90

100

0.40

0.73

1.15

1.39

1.76

2.04

2.39

2.70

3.08

3.40

0.5

0.5

0.5

0.5

0.5

0.5

0.5

0.5

0.5

0.5

0.8

1.46

2.3

2.78

3.52

4.08

4.78

5.4

6.16

6.8

Analysis

When I increased the wire length the resistance also increased.

...read more.

Conclusion

My method was suitable as I got the results I wanted, the experiment could be repeated on a larger scale to make less room for error. The evidence I have for stating that the resistance is proportional to the length is that when the length is 20cm the resistance is 1.46 W and when the length was increased to 40cm, the resistance is 2.78 W. The resistance has roughly doubled, there are other examples of this as well. Length 50cm, resistance 3.52W and when the wire length is doubled the resistance is 6.8 W. I think that better equipment would have given more precise results.

To improve the experiment, the clips could be attached more carefully, a more accurate ammeter would make sure that the current is always exactly the same. A better voltmeter would have given better resistance results. The wires and clips used would also have an effect on the resistance, the wires could be insulated better to reduce heat loss. The results would then contain no anomalies. The above would definitely produce better events.

...read more.

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