Investigating the Resistance of a Wire

Investigating the Resistance of a Wire

We have been given the task to investigate the resistance of different

wires, I am firstly going to start by explaining what resistance is,

why it occurs, what causes it, and how it can be used to our

advantages.

Resistance is a term used to describe the property that various

materials possess to restrict or inhibit the flow of electricity.

Whether or not a material obeys Ohm's law, its resistance can be

described in terms of its resistivity.

The electrical resistance of a wire would be expected to be greater

for a longer wire, less for a wire of larger cross sectional area, and

would be expected to depend upon the material out of which the wire is

made.

Experimentally, the dependence upon these properties is a

straightforward one for a wide range of conditions, and the resistance

of a wire can be expressed as:

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There are a few things that determine the current produced;

* In a conductor, electric current can flow freely, in an insulator it

cannot.

Metals such as copper typify conductors, while most non-metallic

solids are said to be good insulators, having extremely high

resistance to the flow of charge through them. Conductor implies that

the outer electrons of the atoms are loosely bound and free to move

through the material. Most atoms hold on to their electrons tightly

and are insulators.

It is the ability of these electrons to drift from atom to atom which

makes electric current possible.

Other electrons will resist dislodgement and are called bound

electrons. This is known as the free electron theory.

* Temperature has an effect on resistance as the voltage has control

over the temperature.

The more the temperature increases the more the particles vibrate

leading to a reduction in output voltage although not by a huge amount

so this does have an effect.

It is also possible that room temperature may affect our results,

however it shouldn’t.