# Investigating how the resistance of a wire Changes with length

Only available on StudyMode
• Published: April 8, 2004

Text Preview
Aim

The aim of this investigation is to reveal that the factor of length affects the overall resistance. So when changing the length of the conductor does resistance increase or decrease.

Prediction

I predict that as the length of the wire decreases so will the resistance. This is because through a shorter length of wire would allow more current to move through at a higher rate than a longer wire.

When the wire increases then the resistance will increase also. This is because as there is more and more wire there are more obstacles for the electrons to go around.

In my investigation however, relating with the certain lengths I expect twenty centimetres of wire to resolve in the lowest of resistance. Whereas, the length one hundred centimetres, I expect to carry the highest resistance. Therefore I expect more current to flow through on the shortest piece of wire.

Hypothesis

Current flows through a circuit. Resistance is any opposition that prevents current from flowing through a circuit. Resistance is measured in ohms. The way to work out resistance is by this formula: R= V/I. There are many factors that cause and change resistance. Such as temperature, when the particles are heated they receive more energy causing them to vibrate and agitate. This causes more obstacle and obstruction for the electrons to easily pass through. When represented with a longer wire, resistance will increase. This is because it takes much more time for an electron to pass through. A shorter wire will allow current to pass through at a much higher rate. Resistance is also affected by cross sectional area. The wider the wire is the more electrons will pass through at any one time. But length is the most important one in this experiment.

As you can see from the diagram the shorter wire allows more electrons to pass through it at a higher rate. The longer wire though, the electrons are still travelling through the circuit not allowing them to rapidly conduct.

Apparatus

For this experiment I used...

*Ammeter

*Voltmeter

*Wires (with crocodile clips.)

*Battery Pack

*Meter stick

*Nichrome Wire

This diagram of the experiment.

Variables

This particular experiment consists of changing the length of the wire to see the change and affect it has on the resistance. I plan to the take readings current when the voltage is at two, four, six and eight. So I am also changing the voltage, electrical push, as well to find an average resistance.

The dependant variables of this experiment will most obviously be the resistance changing as the length does.

To make this a fair test there are certain control variables. These make the experiment a fair test. This involves keeping the same temperature of the wire. Heat on the atomic or molecular scale is a direct representation of the vibration of the atoms or molecules. Higher temperature means more vibrations. When the wire is cold the protons are not vibrating much so the electrons can run between them fairly rapidly. This means less resistance within the wire. But as the conductor heats up, the protons start vibrating and moving slightly out of position. As their motion becomes more variable they are more likely to get in the way and disrupt the flow of the electrons, as a result, the higher the temperature, the higher the resistance. This is why it is essential to take care of where I perform the experiment, as I did it twice. Also the wire needs to be of the same material and the same cross sectional area. If the wire is very wide, it will allow a high current through it, while a narrow wire would be difficult to get through due to it's restriction to a high rate of flow. Resistance is less in a wire with a larger cross sectional area. All these minor implications can change the eventual outcome of the experiment.

Method

To begin with we collected all the required equipment ammeter, voltmeter, wires (with crocodile clips), battery pack, meter stick,...