investigate the resistance of a wire

hypothesis

the longer the length of wire, the higher the resistance. this is due to the increased length causing more collisions between the current-carrying electrons and the atoms within the wire

outline

record current and voltage readings for the varying lengths of resistance wire

equipment

• a suitable power supply

• ammeter

• voltmeter

• 2 crocodile clips

• resistance wire

• meter rule

• connecting wires

• tape

outline of the method

1. decide on the number of wire lengths to investigate

2. connect the apparatus together to form the circuit you have drawn

3. ensure disconnect the circuit in between measurements, record the current and the voltage for each length of wire chosen to investigate

4. repeat process for the amount of times needed

data analysis

calculate average resistance, plot graph uing equation voltage=current x resistance

what are the two control variables and how would they be controlled

temp of wire, cross-sectional area of wire, which are controlled by switching off the current in between readings and using the same wire for each measurement.

hazard - wire

risk:

• fraying causing risk of electrical shock

precaution

• check condition of wires before usage

hazard - resistance wire

risk:

• can get hot and cause minor burns

precaution

• use low-voltage power supplyand switch off current between readings

evaluation

by switching off the circuit between readings allows for the resistance wire to cool down

• lowering chance of being burnt during the investigation

• ensures constant temp which will secure more accurate results as temp can effect the resistance