A Wire's Length's Effect Resistance

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A Wire's Length's Effect Resistance

Planing

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Aim:

To find out how the length of a nicrome wire affects the resistance.

Prediction:

The longer the wire the more resistance there will be.

[IMAGE]The atoms in the wire are very close together, because the wire

is a solid. The atoms are made of protons, neutrons, and electrons.

[IMAGE][IMAGE] = atom = electron

[IMAGE]In a long piece of wire there are more atoms so there is less

room for the electrons to get through. The electrons bump into the

atoms and lose some of their energy.

[IMAGE]However in a short piece of wire, there are less atoms. This

means that it is easier for the electrons to move through the wire.

The atoms rub against the electrons, and this creates friction. The

friction also creates heat, which makes the wire hot. If the wire gets

too hot, it will melt.

Diagram:

[IMAGE] Battery

Ammetre

[IMAGE]

[IMAGE] Voltmetre Nichome wire

Method:

[IMAGE] Set up the apparatus as shown in the diagram. Using a metre

ruler, measure out 10cm of nicrome wire. Set up the circuit and take

the readings from the voltmetre and the ammetre. Repeat the experiment

with 20,30,40,50,60,70,80, and 90cm of wire. Work out the resistance

using this equation:

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V= voltage

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I= current

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R= resistance

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Safety:

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Make sure your hands are dry when use electricity. Be careful when

handing the wire as it may get hot. Do not let the wire get too hot or

else it will burn out.

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Fair test:

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To keep the experiment fair, I will use the same ammeter, voltmeter,

and power pack, throughout the experiment. To get accurate results I

will use a digital ammeter and voltmeter, and will keep the nicrome

wire the same width throughout the experiment.

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Obtaining evidence

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