Resistance Coursework - Some Useful Things

Resistance Coursework

Planning:

Aim

Investigate how the length of a wire affects the current and resistance of a wire.

Variables

The variables that could change resistance are:

• Length of the wire

• Cross section area (thickness)

• Changing materials

• Changing temperatures

The variable I am going to change in my experiment is the length of the wire.

Prediction and Hypothesis

I think as you increase the length of the Constantan wire, you also increase the amount of resistance. The current is the flow of electrons; the current is dependent on the amount of voltage, which is applied. Voltage is the push given to the current. The current has to go through a circuit, which contains resistance so if you increase that push you also increase the flow of the current. All materials have a slight resistance to electricity factors affecting the resistance are: Length, Voltage & Temperature and Surface Area.

Preliminary Work

Changing only the length of the wire

Length Voltage (V) Current (A) Resistance ()

Short 5.45 0.26 20.96

Long 5.56 0.24 23.16

Longest 5.58 0.19 29.36

Conclusion: the longer the wire, the higher the resistance

Changing only the cross section area of the wire

Thickness Voltage (V) Current (A) Resistance ()

Single 4.73 1.45 3.26

Double 4.44 1.98 2.24

Triple 4.34 2.07 2.09

Conclusion: the thicker the wire, the lower the resistance

Changing Materials

Material Voltage (V) Current (A) Resistance ()

Constantan 5.51 0.48 11.47

Aluminium 1.82 8.63 0.21

Conclusion: different materials conduct electricity better

Changing Temperatures

Temperature Voltage (V) Current (A) Resistance ()

Cold 2.27 6.72 0.34