Resistance is measured in ohms (Ω)
Prediction
I predict that as I will increase the thickness of the wire, the current will increase, the reason being that This is because thick wires have less resistance than thin wires. Also as I decrease the length of the wire the amount of current will increase. This is due to the fact that short wires have less resistance. Therefore the current will flow through more easily.
EXPALIN ABOOUT THE PARTICLES!
I predict that as I will increase the thickness of the wire the current will increase because thick wires have less resistance. Thick wire have less resistance because there is more space which the electricity can pass through easily and for a thin wire the current will decreases, the reason being that there is a high resistance because it is hard for the electricity particles to pass through the wire as easily due to the lack of space.
When l increase the length there will higher the resistance and low current since it will take longer for the electricity to pass through the wire and so a full circuit will take longer. When I make the length smaller there will be less resistance and a high current because it is quicker for the current to complete the circuit.
Plan
Voltage will remain constant throughout of 4v from the battery pack.
For this experiment the factor that I will be considering is the thickness and the length of the wire. I will have a bulb so that I can check that everything is working properly. The independent variable will be the thickness of the wire, I have five different thicknesses and they are 40swg, 36swg, 32swg, 30swg and 22swg. For the length my independent variable will be the length, once again I will be using five different lengths, they are 160cm, 140cm, 120cm, 100cm and 80cm. The dependent variable is the amount of current flowing through. Also by knowing this I can work out the resistance by using the equation. For the thickness of the wire I will need to keep the length of the wire the same throughout the experiment, which is 15cm and that I use the same wire throughout (nichrome). To make it a fair test for the length of the wire I will need to make sure that I use the same type of wire throughout the experiment. I will also have to make sure that the power going through the circuit stays the same. By doing all this, my results will be more accurate. The safety measures that I will have to take will be to make sure that I do not touch the wire whilst the power is on because it can get hot. I will also have to make sure that I have set out the equipment properly so that I do not get a short circuit.
Method
Apparatus: power pack, ammeter, light bulb, insulated wires, wire clips, 5 different thicknesses of nichrome wire, 5 different lengths of wire , ruler to measure the length of wire.
Thickness of wire
- I will set up the equipment as shown below:
- I will measure 15cm of the wire.
- I will then put the power pack on number 4 and then I will put the power on.
- I will check whether the circuit is working properly by checking if the light has lit up.
- I will then measure the current going through and then record my result.
- I will repeat this procedure until I have all of the 5 different thicknesses of the wire.
Length of wire
- I will set up the equipment the same as above.
- I will measure 5 different lengths of wire; they are 160cm, 140cm, 12cm, 100cm and 80cm.
- I will then put the power pack on number 4 and then I will put the power on.
- I will check whether the circuit is working properly by checking if the light has lit up.
- I will then measure the voltage going through and then record my result.
- I will repeat the procedure until I have done all 5 lengths of the wire.
Results
Thickness of the wire
Length of the wire
Analysis
By looking at my table of results and my graph I can tell that as the thickness of the wire increases the amount of current produced decreases. This is because thick wires have more resistance than thin wires therefore it is harder for the current to flow through easily.
I can also see that as you increase the length of the wire the amount of current decreases. This is due to the fact that long wires have more resistance than short wires and so the current is not able to flow through easily.
Both graphs have a negative correlation; this is because in both cases I either increased the length or the thickness of the wire which both have a high resistance. Resistance opposes the flow of electrons. Something with a high resistance limits the amount of current flowing through a circuit for a particular applied voltage.
Evaluation
I think that my investigation answered the question that I was looking for because I learnt how the thickness of a wire can affect the resistance.
I think that I done my experiment quite well because it was easy and it gave me the answers that I needed to know. I also think that it was fair because I made sure that I kept the length of the wire the same throughout and I also made sure that I kept the same amount of power going through the circuit at all times. I think my experiment was fair because I was quite aware of the consequences if I was not careful and accurate.
Although my experiment was quite successful I still feel that there were some weaknesses as well. I think that I should have repeated the experiment for the length 2 more times so than I could have got an accurate result. I also feel that I should have measured the voltage flowing through the circuit using a voltmeter but I did not have the time to do this.
If I was to do this experiment again I would have made various changes to it. I would have repeated the procedure for length 2 more times than I could have got a more accurate result. I would have also measured the amount of voltage flowing through. This way I would learn more about the electrons flowing through the circuit.