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My aim for this investigation is to experiment and find out whether the length of a copper wire in a circuit affects the amount of resistance.

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Introduction

GCSE SCIENCE COURSEWORK

PHYSICS

RESISTANCE OF A WIRE

INVESTIGATION

BY SAIDUR RAHMAN

11U


Aim:

My aim for this investigation is to experiment and find out whether the length of a copper wire in a circuit affects the amount of resistance.

Factors:

 The following are factors which affect the resistance of a wire:

  • Length – this will be the variable in this investigation. The longer the length of the wire, the more resistance there is, resulting in a less current flowing around the circuit.
  • Thickness – there is more resistance if the wire is thick, because there is a larger diameter, there is more wire overall. This means there is more resistance, resulting in a less current flowing around the circuit.
  • Temperature – if the wire is hotter, then there is more resistance. This is because there is more energy in the wire. This means the atoms of the metal vibrate more fiercely. This means that the electrons have more difficulty getting through the wire as they collide with atoms which are in their path. This increases the amount of collisions, which means there is more resistance. This results in less current flowing around the circuit.
  • Voltage – this is obvious, that if there is more voltage, or potential difference, then the less resistance there is.
  • Material – the type of metal the wire is made of also influences the amount of resistance the wire holds. Different metals have different number of electrons, and electricity can go through easier with some metals than others.
...read more.

Middle

3.50

11.67

75

0.28

3.54

12.64

80

0.21

3.58

17.05

My preliminary work results show that the resistance of the wire DOES go up as the length of the wire goes up. However, as this is a preliminary, there could be a lot of mistakes. So to reduce these mistakes, I have chosen to repeat the experiment three times rather than once as was in the preliminary.

Also there were too many results, so I am going to experiment with only lengths of wire in the multiple of ten, up to eighty. This will reduce the number of results I get, but will still clearly give an indication whether my prediction is correct or not.

Plan:

My plan for the investigation is to set up the circuit as follows:

image03.png

  1. I will connect a battery to an ammeter. I WILL BE USING 1 BATTERY FOR THE EXPERIMENTS.
  2. I will then stick copper wire onto a metre ruler
  3. I will clip one end of the wire with a crocodile clip
  4. I will clip the other end of the crocodile clip at another point of the crocodile clip. This point and the end of the copper wire will be equivalent to the length of the wire I am currently investigating.
  5. I will connect the voltmeter in parallel.

I will conduct the experiment three times for every measurement of the wire to avoid any mistakes. I will also make sure the only variable is the length of the wire. As an extra precaution and to achieve the best possible results, I will change the ammeter and voltmeter after every run of the experiment.To make this test fair I should take more than one result so that I can work out an average, this will help prevent any wayward results.


Results Table:

Here are my results for the experiments:

Length of Wire (cm)

Current (A)

Voltage (V)

Resistance (Ohms)

10

2.40

2.30

0.96

20

1.10

2.35

2.14

30

1.03

3.14

3.05

40

0.85

3.20

3.76

50

0.64

3.26

5.09

60

0.44

3.34

7.59

70

0.30

3.49

11.63

80

0.22

3.55

16.14

...read more.

Conclusion


Conclusion:

From the data above, I can conclude that my prediction was correct - that resistance is increased if the length of the wire ascends. This results in a less current round the circuit.

One way the results could have been inaccurate is that I could not keep the temperature of the wire under control. As explained as one of the factors, temperature does make a difference to the resistance. One way I could have overcome this problem is to use a fresh batch of wire every time I conducted the experiment. This way all the wire temperature will be the same.

The higher the resistance, the less current passes through it.

Evaluation:

I enjoyed working and investigating my prediction. My results could have been improved if I have used a fresh batch of wire for each experiment. This would make sure the temperature was the same for each experiment.

Another way I could have improved my results was to use a different set of equipment for each investigation, as some of the equipment was out-of-date, so they are prone to give inaccurate readings, which will affect my results.

...read more.

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