The Factors Affecting the Resistance of a Wire

Resistance (R) = p.d across the wire (V)

Current through the wire (I)

R = V

I

V = IR

In most electrical, conductors are used in the form of a wires, so the nature of the resistance of a wire to an electric current must first be investigated.

Aim - To study how one particular factor affects resistance.

Variables that affect the resistance of a wire

. Material, type of Metal. 5. Pressure

2. Temperature 6. Dimension (coiled)

3. Length 7. Magnetic Field

4. Thickness

Key Variables that affect the resistance of a wire

. Temperature

2. Material

3. Wire length

4. Wire width

Prediction

Temperature If the wire is heated up the atoms in the wire will start to vibrate because of increase in energy. This causes more collisions between the electrons and the atoms as the atoms are moving into the path of the electrons. Increase in collisions means that there will be an increase in resistance.

Material: The type of material will affect the amount of free electrons that are able to flow the wire. The number of electrons depends on the amount of electrons in the outer energy shell of the atoms, so if there are more or larger atoms then there must be more electrons available. If the material has a high number of atoms there will be high number of electrons causing a lower resistance because of the increase in the number of electrons. Also if the atoms in the material are closely packed then the electrons will have more frequent collisions and the resistance will increase.

Wire length: If the length of the wire is increased then the resistance will also increase as the electrons will have a longer distance to travel and so more collisions will occur. Due to this the length increase should be proportional to the resistance increase.

Wire width: If the wires width is increased the resistance will decrease. This is because of the increase in the space for the electrons to travel through. Due to this increased space between the electrons there will be less collisions and the resistance will decrease.

Preliminary work

We will do extensive research on which width of wire is available in different materials in order to find the materials that will give us the best possible results.