Gcse Physics Coursework – 2005/2006
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GCSE Physics coursework – 2005/2006.
Introduction.
According to ohms law, a higher resistance simply means a larger amount of energy is used to move the electrons through the wire as they collide with the atoms. Therefore resistance is measurement of how much energy is used to push the current through a substance or material.
In this experiment I will be judging the connection between a wires length and its resistance. In theory, if I were to half the length of a wire the amount of moving electrons would be halved and therefore the amount of collisions between the atoms and electrons would be halved as well.
Practical Procedure.
Apparatus.
*NOTE* I have selected the chosen apparatus from a range of equipment, the chosen apparatus happened to be the most efficient.
I will need one meter of Nichrome wire, a power pack to use as a source power, a voltmeter to measure the exact amount of volts being passed through the Nichrome, two crocodile clips attached to wire, so that I can connect the power pack to the Nichrome, an extra two wires so that I can hook up the voltmeter into the circuit, and a mains plug socket to plug the power pack into, I will also be needing an ammeter to measure the current and another wire will be needed to hook that up as well.
Once everything is connected, the circuit will look like this.
Method.
There are four factors that affect the resistances of a wire, each are of equal affect: Diameter/thickness, Length, Metal type, Temperature.
From evaluating how I would carry out the experiment and the outcome of it. Ive come to the conclusion that the length would be the best variable.
To create a better accuracy in comparison to my preliminary testing a meter ruler will be placed on top of the bench that is being worked on. A piece of masking tape will be applied at both ends of the meter rule with the nichrome wire stretched out along the rule. This will make it more accurate and easy to place crocodile clips on the correct measurements, as the wire will be straight and wont coil.
Firstly, connect the Power Pack into a plug socket.
Plug in two wires into the power pack, making sure that one of the wires has a crocodile clip on the end, attach this crocodile clip to one end of the Nichrome wire securely.
With the other wire coming out of the power pack attach it to one side of the ammeter.
Take another wire with a crocodile clip at one end and plug it into the other side of the ammeter.
Attach the crocodile clip to the other end of the Nichrome wire so that it is able to move with little resistance, up and down
Take two wires and attach one to one of the crocodile clips, and attach the other wire to the other crocodile clip.
Your will now have two loose ends, plug these into the voltmeter. Your circuit is now set up
Turn on the power pack and begin.
With measurements ranging from 100cm to 20cm, by decreasing the length by 20cm five times, I can collect enough data to be able to plot a reasonably reliable graph that will display a trend effectively. The data collected will be shown in the form of resistance. Resistance is measured in ohms. Resistance can be worked out by using this simple formula.
Safety factors
When conducting the experiment make sure no water or any other liquid is present.
Wires have sharp edges avoid direct contact with the ends.
Do not cross any live wires as it may cause sparks, which in turn can short out the power pack and cause it to reset.
Make sure Nichrome wire does not coil as it may short out and over heat.
Use a voltage of 2v as when conducting preliminary experiments it was acknowledges that this was the best voltage