I will be studying the resistance of wire, to gain a better understanding of resistance and connecting topics.

Resistance of wire

Rebecca Doorbar

PLAN

Aim: I will be studying the resistance of wire, to gain a better understanding of resistance and connecting topics.

Resistance is caused when electrons flowing along a wire collide with the particles of the wire. These collisions slow down the electrical flow which causes resistance.

The reason why metals are such good conductors is because they contain free electrons. The amount the electrons are able to move about depends on the arrangement of atoms within the metal. E.g. copper has a structure allowing free and easy movement of electrons, in contrast with iron which does not. The amount that the structure of the metal slows down the electrons is the resistance.

Good conductors have low resistance; bad conductors have high resistance. This is why it is important to be aware of the factors that affect resistance in a wire, because they can make wires good for certain uses and not others. Temperature is one of the most important factors that affect resistance. Ohm’s law states that if all the factors that affect resistance in a wire remain constant, THEN the current is directly proportional to the p.d. across it.

Resistance is responsible for the current that flows – high resistance produces a low current and low resistance a high current. Resistance is often evident as the conversion of electrical energy to heat. I might expect the wire to get hot to show that there is resistance.

RESISTIVITY is a property of a conductor that tells you how hard it is to push current through it. Resistivity is independent of the dimensions or shape of the material.

Relationship between resistance, resistivity, length of wire and its x-sectional area is:

Resistance = Resistivity x length

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