Factors Affecting the Resistance of Wire

Aim: To investigate the factors that affect the resistance in a conductor. The main factors that affect the resistance in a conductor are:

· Length

· Temperature

· Cross sectional area

· Material

· Magnetism

The factor that we are going to change is the cross sectional area.

Hypothesis: I think that the higher the cross sectional area, the lower the resistance in the conductor will be. This is because the Resistance in a metal conductor happens because as the electrons move through the material (once a voltage has been applied) they collide with the atoms in the material and as a result lose some of their energy. The idea of resistance is simply how difficult it is for the electrons to move through a material. The more difficult it is, the more energy they lose in the material on their travels.

We define electrical resistance as the ratio of voltage to current.

The equation we use to find the resistance from the current and voltage is:

Resistance (R) = Voltage (V) ÷ Current (I)

Put more simply, it is the number of volts difference across the object when one amp of current flows. You should recall that voltage is the number of joules of energy transferred by one coulomb of charge, and that current is the number of coulombs of charge passing a place each second.

What the object is made of will have an effect on its resistance. Not all metals even are equally as good at conducting electricity. A longer length will also make it more difficult for current to flow, as there is more material to travel through.

The temperature of a metallic conductor will also affect the resistance. A hot metal has a larger resistance than a cooler one, but this is tricky to test reliably in the laboratory because the temperature has to be a lot higher to get a decent change in resistance.

Current is nothing but the rate of flow:

But when the temperature rise takes place, the lattice atoms also vibrate in their own equilibrium more vigorously impeding the flow