Investigation into how the resistance of a wire can vary.

Investigation into how the resistance of a wire can vary

The resistance of a wire can be affected by many different factors. I am going to look at all the possible variables, and see which factor I am going to study more closely, and then see how it effects the resistance of the wire. Resistance occurs when the electrons travelling along the wire collide with the atoms of the wire. These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire.

“Electrical resistance” itself is the opposition of the flow of electrons in the wire. Ohm’s law states that the potential difference (voltage), and the current, are proportional to each other provided that the temperature remains constant.

V = I x R

Voltage = Current x Resistance

There are 4 main variables in the resistance of a wire, which all affect

1.Temperature- If the wire is heated, the atoms inside the wire start to vibrate because of this increase in energy. This therefore causes the atoms to collide with electrons. This increase in collisions means that there will be an increase in resistance.

2. Material- The metal that the wire is made out of will affect the free electrons ability to flow through the wire. The number of electrons depends on the amount of electrons in ...

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V = I x R

Voltage = Current x Resistance

There are 4 main variables in the resistance of a wire, which all affect

2. Material- The metal that the wire is made out of will affect the free electrons ability to flow through the wire. The number of electrons depends on the amount of electrons in the outer energy shell of the atoms. If there are more atoms, then there will be more electrons available. A high number of atoms means the number of electrons will increase too, causing higher resistance. If the atoms in the material are closely packed, then there will be more frequent collisions and the resistance will increase.

3. Wire length- If the wire length is increased then the resistance will also increase. This is because the electrons have longer to travel, and therefore more collisions will occur.

4. Wire width- If the width of the wire is increased the resistance will decrease. This is because there is more space for the electrons to travel through. If the wire is thicker, the electrons are less tightly packed in there, and so there is more space, which means there will be fewer collisions with atoms.

I am going to investigate how the length of the wire affects the electrical resistance, as this is a simple, yet affective way of getting accurate results.

Prediction

I predict that increasing the length of the wire will proportionally increase the resistance. I think this because the longer the wire the more atoms there are, and so it is probable that more electrons are going to collide with atoms. This is because if the length of the wire is doubled the number of atoms will also double resulting in twice the number of collisions slowing the electrons down and increasing the resistance.

Method

I have chosen to use wire with a thickness of 30SWG. This is because I found that this wire has a very high resistance. This will be the best wire to use, as it will be easier to measure the resistance. To collect the data for my graph I have chosen to take a range of 5 lengths. I have chosen a range of 5 as I will get a good range of results from these, and it will be easier to plot an accurate graph with them. This will give me a better result overall.

I will record the resistance at each of the following lengths-
5 cm
10cm
15cm
20cm
25cm

When I record the results of each length, I am going to take 5 measurements of the resistance, from 5 different places on the wire. Therefore I will have 5 results, and I can average them to give me a more accurate resistance.

Once I have both the voltage and the current for each of the 5 sets of readings on each wire length, I am able to calculate the resistance using Ohm’s law.

Resistance = Voltage ÷ Current

I am going to work out the resistance of each measurement this way.