Resistance Essay Research Paper The four factors

Resistance Essay, Research Paper

The four factors that affect the resistance of a piece of wire:

Length,

Diameter or thickness,

Temperature and

The type of metal.

From thinking about how I would do this investigation and the outcome of it, I decided to use the length of the wire as the variable. Aim The aim of my investigation is to investigate how length affects the resistance of a length of wire Resistance is the force, which opposes the flow of an electric current around a circuit so that energy is required to push the charged particles around the circuit. Resistance is measured in ohms. A resistor has the resistance of one ohm if a voltage of one volt is requires to push the current of one amp through it.

Resistance occurs when the electrons travelling along the wire collide with the atoms of the wire.

These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire.

Wire length: If the length of the wire is increased then the resistance will also increase as the electrons will have a longer distance to travel and so more collisions will occur. Due to this, the length increase should be directly proportional to the resistance increase.

To measure and record the results for this factor is simple, the results would be collected and could show a connection between the length of the wire and the resistance given by the wire. This is why I have chosen to investigate how resistance changes with length.

Ohms law, V=I/R. This says that for a certain current (charge flowing at a certain rate), there will be a greater voltage across the wire if it has more resistance.

This tells me that the voltage measures the amount of energy used up in getting each coulomb of charge through the wire. The units of volts are the same as joules per coulomb. Therefore, Ohms law says the more resistance means more energy used to pass through the wire. Resistance is a measure of how much energy is needed to push the current through something. The electrons carrying the charge are trying to move through the wire, but the wire is full of atoms that keep colliding in the way and making the electrons use more energy. Preliminary Method In this preliminary experiment, I will use different lengths of wires to measure their resistance. The main idea of doing the preliminary experiment was to find a suitable current number to put the power supply on. I also wanted to do this experiment to familiarise myself further with the method; if I had any problems I could correct them there and then. This would mean I would obtain precise and reliable results in my main experiment when investigating the connection between the length of the wire and the resistance of the wire.

First, the circuit was set up as shown below. I had to be careful in connecting circuit, because the Voltmeter had to be placed in parallel and the ammeter, which had to be placed in series. Draw up a rough table onto a piece of paper with the appropriate headings. The wire was cut to just over 50cm so the crocodile clips could attach onto the wire, making the results more accurate. Stretch out the wire onto the bench and measure with a metre rule. The power supply was put on 2V and the gradually increased the 4V, to find a suitable current for my main method. The slider on the resistor was moved to allow me to do five repeats. I decided to go down in ten centimetre gaps, as it would allow me to lot a graph of resistance against length with a range of fie readings. Results As shown below there is only a range of five readings, which start to show a pattern, that the best fit line is directly proportional. To see if this trend carries on, I will widen my main experiment and use a 100cm length of wire, I will also take the readings every 5cm and not 10cm. From my experimentation with the power supply, I have decided to keep it at 4V, as I do not need the wire length to go lower than 10cm. Length (cm)Current (Amps, A )Voltage (Volts, )Resistance (Ohms, )Average resistance (Ohms, )

500.250.220.350.290.430.340.300.520.330.441.411.361.491.131.021.54

400.270.180.140.110.090.340.230.180.140.121.261.271.281.271.321.28

300.270.190.150.120.100.260.180.140.110.100.960.950.930.911.000.97

200.350.160.120.090.070.230.110.080.060.050.660.690.660.660.710.68

100.270.190.130.100.070.100.060.050.030.020.370.320.380.310.290.33

Main Experiment Prediction I predict that if the length increases then the resistance will also increase in proportional to the length. I think this because the longer the wire the more atoms and so the more likely the electrons are going to collide with the atoms. Therefore, if the length is doubled the resistance should also double. This is because if the length is doubled the number of atoms will also double resulting in twice the number of collisions slowing the electrons down and increasing the resistance. My graph should show that the Length is directly proportional to the resistance.

If the length of the wire is only half the length of the wire on the same type of wire, there should be half the number of collisions between the electrons and the atoms.

If the wire is twice as long, there should be twice the number of atoms, resulting in twice as many collisions and a pr

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