Factors Affecting the Resistance of Wire

1883 Words Apr 4th, 2005 8 Pages
Aim: To investigate the factors that affect the resistance in a conductor. The main factors that affect the resistance in a conductor are:

· Length

· Temperature

· Cross sectional area

· Material

· Magnetism

The factor that we are going to change is the cross sectional area.

Hypothesis: I think that the higher the cross sectional area, the lower the resistance in the conductor will be. This is because the Resistance in a metal conductor happens because as the electrons move through the material (once a voltage has been applied) they collide with the atoms in the material and as a result lose some of their energy. The idea of resistance is simply how difficult it is for the electrons to move through a material. The more difficult
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The equation implies that the resistance is inversely proportional to cross-section, so doubling the cross section should halve the resistance.

Prediction Graph:

Preliminary work:

The circuit (above) shows how we set up the circuit for our preliminary work and our experiments. In our preliminary work, we used some constantan wire in a circuit like above and used it to see what voltage is best to keep the same to find the current and resistance. We found that 3 volts was a good voltage because the current not too high or too low to get a good resistance.

We also did some preliminary work to see if there is a difference weather the two wires are apart from each other or constantly touching each other at all parts, all the time. Our preliminary findings were that it makes no difference. Since it made no difference, we decided to keep them separated so we don't have to twist the wires around each other.

We also had to work out the cross sectional area of the wires. We knew that the diameter for one wire was 0.25mm. We used the following formula to work out the cross sectional area:

Cross Sectional Area = Õr²

r = the radius of the wire. The radius is half the diameter so it should therefore be 0.125mm.

Using the formula, I have worked out the Cross Sectional Area for all the wires I will use. To get the Cross Sectional Area for two wires together you multiply what you found for the first wire by two, for three wires you multiply by 3
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