What Factors Affect the Resistance In a piece of wire?

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What Factors Affect the Resistance       

In a piece of wire?

Introduction:

  Electric current traveling through a piece of wire is a flow of free electrons. As electrons are negative they travel from the negative terminal to the positive terminal as opposite charges attract and like charges repel. This means they are pushed from the negative terminal and attracted back to the positive terminal.

  As the free electrons flow round the circuit, they collide with the vibrating atoms in the wire it is traveling through.

  As the electrons hit the vibrating atoms they give off some of their kinetic energy and slow down. This is how current is resisted.

Variables:

Temperature: As temperature increases the resistance in the wire will increase. This is because when the wire is heated up, the atoms in the wire are given more energy and so vibrate much more and much faster. This means that the free electrons flowing around the circuit will collide more with these atoms and will lose some of their kinetic energy, therefore resisting the current more.

Diameter of wire: The smaller the width the smaller the resistance. This is because an a thicker piece of wire there are more atoms for the free electrons to collide with so the resistance will increase, because the electrons will be giving off some of their kinetic energy and slow down.

Material: Using different materials will affect the resistance in a piece of wire. This is because in different materials there are different numbers of free electrons to each individual atom, because different metals have different valences. Therefore if one metal for example, had more free electrons to each atom then there would be less resistance because there would be more current flowing round the circuit.

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  I will investigate how the length of a wire affects the resistance in the wire.

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Prediction: I think that when the length of the wire is increased the resistance in the wire will also increase. This is because there are more atoms in a longer piece of wire than a smaller piece of wire. This means that the free electrons traveling through the wire will collide with the atoms of the wire more. This means that the free electrons are continually giving off some of their kinetic energy in the collisions, so as there are more collisions ...

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