Investigating the Resistance of a Wire

Investigating the Resistance of a Wire

Aim: I am going to investigate what factors affect the resistance of a

wire.

Here are some main factors which may affect the resistance of a wire

* Length

* Thickness

* Temperature

* Voltage

* Resistance

* Material

Resistance is a force which opposes the flow of an electric current

around a circuit so that energy is required to push the charged

particles around the circuit. The circuit itself can resist the flow

of particles if the wires are either very thin or very long.

Resistance is measured in ohms. The symbol for an ohm isOmega Symbol.

A resistor has the resistance of one ohm if a voltage of one volt is

required to push a current of one amp through it.

George Ohm discovered that the emf of a circuit is directly

proportional to the current flowing through the circuit. This means

that if you triple one, you triple the other He also discovered that a

circuit sometimes resisted the flow of electricity. He called this

resistance. He then came up with a rule for working out the resistance

of a circuit:

V - volts

I - current

R – resistance

V/I = R or v = I x R

I therefore predict that as I increase the length of constantan the

resistance will increase due to the doubling of electrons which create

resistance.

Method

methodApparatus: Voltmeter, ammeter, 2 crocodile clips, power pack

Set apparatus up like so:

First a length of wire is sellotaped to a metre rule. The positive

crocodile clip is attached at 0cm. And the negative is moved up and

down the wire, stopping at 20, 40, 60, 80 and 100cm. Each time reading

the ammeter and voltmeter to work out resistance R = V/I. Other

variables, voltage, thickness, and temperature will be kept constant,

although the temperature will rise once current is passing through it,