Resistance of a Wire

Resistance of a Wire

I have been asked to solve the problem of getting a resistance of 1.9

ohms using resistance wire. Resistance is how easily a potential

difference is carried across a conductor. The higher the resistance,

the bigger the potential difference has to be to go through the

conductor. To do and understand this investigation I must see firstly

what factors are involved when looking at resistance. I have come up

with six things which affect the resistance in a wire:-

Thickness-

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If the wire is very thick i.e. it has a big cross sectional area

(csa). It will have a smaller resistance than one with a smaller csa.

This is because electric current in a metal is made up of electrons

jumping and hitting more electrons, like dominoes. The metal ions in

the wire block some electrons, causing a resistance. If there is a

bigger area through which the electrons have to squeeze, the

resistance will evidently be lower.

Material of Wire-

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This is quite an obvious one, as I know that all materials have

different conductivity. For example copper is a better conductor than

tungsten but silver is the best. By knowing what the conductivity of a

material is, I know how much resistance it would have, as the better

the conductor the less the resistance.

Temperature-

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As temperature increases so does resistance. If a wire has a high

temperature, then the ions in the wire will be vibrating more. This

means there are more collisions between the ions and the electrons

trying to get past. This would result in a greater resistance. It

could be likened to a packed corridor in a school. If you are going

one way, and everyone else is going the other, it is easier to get

past them if they are still and not moving.

Length of Wire-

As the length of the wire increases, the resistance should increase

too. This is because since there is more length, there would be more