Resistance in wire.

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Resistance in wire

Aim

To investigate how the electrical resistance of a wire changes in relationship to its length.

Prediction

I predict that as the length of the wire increases so will the resistance. I also believe that the rate of resistance of the wire increases will be directly proportional to the length. Electricity, the property that transforms electrical energy into heat energy, in opposing electrical current, is resistance. A property of the atoms of all conductors is that they have free electrons in the outer shell of their structure. All metals are conductors.

As a result of the structure of all conductive atoms, the outer electrons are able to move about freely even in a solid. When there is a potential difference across a conductive material all of the free electrons arrange themselves in lines moving in the same direction. This forms an electrical current. Resistance is encountered when the charged particles that make up the current collide with other fixed particles in the material. As the resistance of a material increases so to must the force required driving the same amount of current. As the length of the wire is increased the number of collisions the current carrying charged particles make with fixed particles also increases and therefore the value for the resistance of the wire becomes higher. The material and cross sectional area of the wire is constant throughout the experiment, so the resistance should be directly proportional to the length of wire.

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Method

I will begin by connecting the circuit as shown below in my diagram. I will use the voltmeter to record the voltage. I will use the following lengths of wire to record my results; 100cm, 90cm, 80cm, 60cm, 50cm, 30cm and 20cm. I will use Ohms law resistance in ohms; (R) is equal to volts (V) divided by current in amps (I).

Equipment

Power pack

Voltmeter

Ammeter

1 metre long wire

Two crocodile clips

Fair test

When carrying out this experiment I will only change one thing, the length of the wire. ...

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