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Investigating the resistance of a wire.

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Introduction

Investigating the resistance of a wire

I have chosen to investigate the length of the wire.

        As the length of the wire increases so does the resistance.

The above prediction (as the length of the wire increases so does the resistance) I believe to be true, because a wire is made up of atoms and as you increase the length of the wire the amount of atoms increases as well. As the electrons go through the wire they collide with atoms and decrease in speed. As you increase the length of the wire, there are more atoms and the electrons collide with them more, losing energy and slowing down, there fore the resistance increases because it is more difficult for the electrons to get through. The resistance increases proportionally to the length of the wire. Resistors in a series are added together to give total resistance so adding on another 10cms of wire is like adding on another resistor.

To test my prediction I will need:

  • 10 different lengths of wire (to test – copper – 0.1mm thick)
  • An ammeter (to read the current – digital)
  • A power pack (for the volts)
  • Crocodile clips – wire.

To test the resistance in a wire I will use the formula   R=V/I

V= p.d in volts (v)

...read more.

Middle

These are my results from testing the wire.

Length of wire (cm’s)

Exp. 1 current    (amps)

Exp. 2 current (amps)

Exp. 3 current (amps)

Average current

10

7.83

7.80

7.70

7.78

20

5.72

5.76

5.74

5.74

30

4.59

4.60

4.61

4.60

40

3.76

3.72

3.77

3.75

50

3.26

3.27

2.29

3.27

60

2.82

2.84

2.86

2.84

70

2.53

2.54

2.55

2.54

80

2.30

2.29

2.31

2.30

90

2.07

2.08

2.09

2.08

100

1.88

1.90

1.89

1.89

I then take these results and use the formula   R=V/I.

Take the voltage, which is 6 and divide

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Conclusion

I found that as I increased the length of the wire the resistance also increased, this is because the wire is made up of atoms, and as you increase the length of the wire the atoms inside it also increase. As the current passes through the wire it collides with the atoms in the wire and there are more atoms and less current it is harder for the current to get through. My graph shows and my results show that as the length of the wire increases so does the resistance. My results are quite good, I have no rouge results and my results are relatively on the line of best fit.

I believe that the results collected are sufficient to have firm conclusions, but the more results you have the more firm conclusions can be drawn.

I could improve my experiment by using a wire with a higher resistivity than copper; this would minimize the effects of the circuit wires on the final readings. I could have used Nichrome, which has a resistivity of about 65 times higher than copper.

...read more.

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

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