Resistance of a Wire - Triple Science

by pilot96 (student)

Ejiro Ighoraie

Physics GCSE

In this case study, I will be investigating what affects resistance; I will be looking at the different aspects, and comparing them during the investigations, which will be taking place in class.

I will be doing my investigations and experiments with my peer 'Coelbie Powell'.

Resistance is the ability for a component to prevent or resist the flow of an electrical current. This component would resist the electrical current due to the collision between the electrons and atoms, this then slows down and converts some of the energy, into heat energy. “'n some cases, the energy is also converted into light'.

Diagram

Four Main things that I was able to change about the wire to change its resistance was:

Thickness – When using a thin wire, there is less room for the electrons to move, so the electrons are being prevented to flow.
Using a different material – Using a different material will determine the different atoms. Some atoms will charge better than others, therefore will be a better conductor. This means that there is less moving charges to carry the current. Many other atoms will be willing to lose electrons on their outer shells. This is why the resistance of a wire depends on the configuration of the atoms that the material of the wire is made from.
Length – When increasing the length of the wire, it increases the length of the path that the moving charges have to pass, so the charges are likely to face collisions with other atoms that are not moving.
Temperature of the wire – Once increasing the temperature of the wire, it increases the resistance because the atoms of the wire gain more energy as it heats up. When the atoms heat up, they vibrate faster, causing more collisions, which then increase the amount of resistance.

Length gave the biggest variation in resistance and that thickness didn’t change the resistance much. Also that temperature was too difficult to control and measure. That’s why you decided to investigate length.

In the investigation it was vital to keep all the factors the same because if I did not, then it would make the results inaccurate, and give me inaccurate conclusions.

When trying to keep the material of the wire the same, it should be quite simple because all that needs to be done is to be aware of the certain wires and what packages the wires are coming from, so that I do not get mixed up.

Keeping the temperature the same will be quite hard, because controlling the temperature will be challenging.

Keeping the factors the same:

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This is a preview of the whole essay

In the investigation it was vital to keep all the factors the same because if I did not, then it would make the results inaccurate, and give me inaccurate conclusions.

Keeping the temperature the same will be quite hard, because controlling the temperature will be challenging.

Keeping the factors the same:

It is vital to keep all the factors the same because it will interfere with the results and I will fail to get to the true value, so the investigation will not be reliable.

Preliminary Tests

The material used was constantan

Range

My longest will be 100cm, because 150cm was too long. The shortest length will be 10cm, because 5cm seemed to be too short, and while observing peers experiments, I saw 5cm wasn’t a good length due to lack of range.

Thickness

I decided to choose the thick material because there is more room for the current to flow, and the material could become a health hazard if it was a shorter length.

Power Pack Settings

I decided to choose 2V because it showed a good result and didn’t become too hot like 3V or absolute no change like 1V.

The Interval?

Practical set up:

I decided to arrange the circuit having the volt meter vertical across from the power pack, while the ammeter is connected on the left hand side to the power pack and by using a ruler to keep the wire straight so it is more accurate.

I also will be measuring the wire using a meter ruler and will be keeping the temperature down by keeping the power pack level at 2volts.

Apparatus

1 Metre Ruler
1 Power Pack
Sellotape
Variable Resistor
Ammeter
Voltmeter
Constantan wire

Method

I connected my circuit together as shown in the diagram above. I attached the wire to the meter ruler using pins. As I carried on doing the experiment I adjusted some of the wires to make sure everything was correct and in place.

Steps:

Adjust one metre length of constantan wire onto the metre ruler, and added the pins
Adjust and connect all the wires together
Turning on the power pack. The voltage and current are then read off the ammeter and voltmeter
The power supply then turned off, and the crocodile clip moved to the next position

I counted the seconds of how long the power pack was on for to test for the investigation, my partner then read the results, and wrote it down, while I moved the clip to the next position. I double checked my results, making sure I was close to the true value, so I had no outliers.

Results

When doing my experiment on the different lengths of the wire, I double checked everything, to ensure that everything was correct, and there was no in-corrections. I recorded my results in the table below:

I saw that I had no outliers. I then calculated the means of the voltage, current and then from that calculated the resistance (V/I).

From the tests and my graph, I acknowledged that the longer the wire, the larger the resistance. My graph gives a positive correlation.

When I doubled the length of the wire, the resistance also doubled, for example, when the wire was 10cm, the resistance was 0.15 (Ω), When the wire is 20cm, the resistance was 0.31cm. Therefore, the fact that the resistance increases with the length, I have gathered that the longer the piece of the wire, the further the electrons have to travel, which means there are more ions for the electrons to bump into, so when the length of the wire doubles, the more ions there are for the electrons to bump into, which makes the resistance increase.

As the length increases, the resistance of the current increases because the current has further to go through in the wire, thus it has to go past more stationary atoms, which cause more collisions, and therefore there is more resistance.

However, I believe that my results are reasonably reliable, because i repeated my experiment twice, and i double checked my calculations for the mean. My line on the graph, were mainly on the best line of fit.

Fair Test

To ensure that my tests and results were fair, I had to keep variable the same. The variables that I had to keep the same where the temperature of the wire, due to the face that the wire gained more thermal energy as the ions began to vibrate (This would sometimes become a problem when the wire was ‘10cm’, because the wire was not as long.) However it seemed to be fine, which was expected because I chose ‘constantan’, which is proven to have a very low temperature increase.

Another factor that I had to keep the same is the material of the wire because depending on the material, each material conducts different amounts of heat, which would affect the resistance.

Reliability

To make sure that my readings were all reliable, I had to double check and repeat my experiment again, so that I could spot any errors in my results. Using the wide range of lengths from 10cm to 1 metre allowed me to get a good range of results so that I could make a good conclusion.

Accuracy

To make sure that my test was accurate, I had to control the various procedures of the tests. One way in which I did this, was to measure the length of the constantan. The reason why I did this is to make sure that all my tests were accurate, and that my results would be close to the true value, or at least reliable.

Safety

To make sure that all the tests are done safely, the power pack settings will be under 5 volts, so that the constantan wire will not get too hot and burn. If I did not take this safety measure into consideration then it could damage and affect the experiment, and give un-reliable results. Also all bags and outdoor clothing will be away from the experiment, in case any heat causes any accidents.

Evaluation

At the start of the investigation, I don’t believe that I started off to well, as I was behind the rest of my peers, because my partner and I was a bit confused. However, when I understood what I was doing, I soon caught up, and was off to a flying start. The length investigations went very smoothly.

I did find that sometimes, it was quite difficult to be accurate with whether the tip of the crocodile clip was exactly on the measurement I wanted, because it would make around etc. One way I could have made sure that I was doing this accurately, was to make sure I pinpointed, If I had ensured this, I would have got more accurate readings, and much more precise measurements.

Copper Atoms

Electrons

3rd Test

2nd Test

1st Test