See whether the length of wire would effect the resistance.

Treeshan Lalsing 10DH 16/12/02

Resistance Investigation

Aim- The aim of this investigation is to see whether the length of wire would effect the resistance.

Prediction- I think that as the length of the wire increases, so to will the resistance of the wire. I also believe that the rate at which the resistance of the wire increases will be directly proportional to the length of the wire. Therefore the shorter the wire the less the resistance will be in the wire. This is the reason, because the shorter the wire is the less amount of atoms present in the wire to hinder the progress of the electrons flowing through (resisting the electrons).

With electricity, the property that transforms electrical energy into heat energy, in opposing electrical current, is resistance. A property of the atoms of all conductors is that they have free electrons in the outer shell of their structure. All metals are conductors and have an arrangement in similar form to this:

As a result of the structure of all conductive atoms, the outer electrons are able to move about freely even when in a solid. When there is a (P.D) potential difference across a conductive material all of the free electrons arrange themselves in lines moving in the same direction. This forms an electrical current, resistance is encountered when the charged particles that make up the current meet head on with other fixed particles in the material. As the resistance of a material increases so to must the force required to drive the same amount of current. In fact resistance, in ohms(R) is equal to the electromotive force or potential difference, in volts (V) divided by the current, – this is called Ohm’s law.

As the length of the wire is increased the number of collisions the current carrying charged particles make with fixed particles also increases, therefore the value for the resistance of the wire becomes higher. The material and cross sectional area of the wire is constant throughout the experiment.

The main thing in this experiment we will only change one factor, the length of the wire. This should effect the resistance of the wire in the ways stated above.

To make it a fair test in this experiment we are only changing one factor which is the length of the wire, ...

This is a preview of the whole essay

The main thing in this experiment we will only change one factor, the length of the wire. This should effect the resistance of the wire in the ways stated above.

To make it a fair test in this experiment we are only changing one factor which is the length of the wire, the factors that we are going to keep the same are as follows:

We must keep the surrounding room temperature the same or the particles in the wire will move faster (if the temperature is increased) and this will therefore have an effect on the resistance.

The cross sectional area of the wire must be kept constant throughout as well. The material of the wire must also be kept the same as different materials have different conductivity. The last two factors will be kept the same by using the same wire all of the way through the experiment.

The current that we pass through the wire is to be kept the same, also. If this is changed the temperature of the wire might change in a way that is not constant making the results more confusing.

Method

*I connected the wire to the circuit by the crocodile clips,
*I took the voltage and current readings from the meters.
*I kept the supply from the power pack and took the readings again (three times).

*I repeated the test with different lengths of wire.
Safety precautions
I had to make sure that the circuit was properly connected before turning the power supply on, and that I do not touch the apparatus, the power is switched off.
I had to make sure the changing of the tested wires should only occur when the power is off.
I had to make sure that I did not carry out the experiment in wet areas, as water is a very good conductor of electricity, therefore causing electrocutions.
I also had to make sure that I did not switch on the power pack when there is no resistant wire.

Variables

What I will keep the same to make this a fair test is I will keep the voltage the same and I would keep the type wire the same but I not keep the length of wire the same as I am measuring 100cm down to 10cm. What I will be collecting is the voltage and the current to find the resistance. I will find the resistance by using OHM’S LAW, which is VOLTAGE=CURRENT X RESISTANCE, and rearranging the formula in to resistance- voltage/current.

Results

Table-resistance

Conclusion

What my results tell me, is that the longer the length of the wire the higher the resistance will be, because the resistance of the 100cm piece of wire had a resistance of 21.6, this is the highest resistance out of all the other lengths of wires. Although I do think that I did something wrong with the 80cm piece of wire because the resistance measured at 4.3.

Evaluation

My result fits perfectly with my prediction, which was if we increase the length of wire there would be more resistance.

I think this is a good to test out the prediction as I can find the voltage and the current to find out the resistance. In the end in think I could of collected more results to make your sample a little and the results would be more reliable but the good thing was that I collected my results accurately but the graph shows us that the 30cm average was a little iffy because it didn’t come in to the line on the line of best fit. I am not calling it anomalies. My information is reliable because when you increase the length of the wire there is going to be more cracks along the wire and the electrons would not bounce off it.

We can do some further work that we can carry out to provide us with some relevant evidence. We can do this by trying to measure the difference in diameter by raping pieces of wire around each other like below.

The evidence it would give us is when we as an extra wire it so go up twice the time as the first go and when you put another piece of wire on it would be three times the first go.