My investigation was to find the resistance of a wire, by measuring the voltage and current that passes through it. This was done with different lengths of wire. And by using the formula:R = V I

PRELIMINARY

        RESISTANCE =        3m        - 3.2

                                 2.5m        - 2.6

                                2m        - 1.7

                                1.5m        - 3.5

                                1m        - 3.5

                                0.5m        - 4

VARIABLES

                  LENGTH OF WIRE – the longer the piece of wire, a higher resistance will be found.  This is because electrons collide with the wire particles.  The further it has to go the more particles it will collide with, so the resistance will be greater.

THICKNESS OF WIRE – the thicker the wire the lower the resistance.  This is because there is more room for the electrons to flow through the wire.

TEMPERATURE – particles will move around a lot more if the temperature is increased, I will be keeping the temperature at a constant room temperature.

FAIR TESTING

          To ensure that the investigation is carried out in a fair way and that the results will be accurate and reliable a number of things must be followed. The only variable in the test I will be performing will be the length of the wire. The wire must be pulled tight against the ruler and taped in place to ensure the length is accurately measured. The experiment should be repeated 2 or 3 times and an average taken to make sure that the results are reliable.

EQUIPMENT

·        Power supply

·        Ammeter

·        Digital voltmeter

·        Crocodile clips (x3)

·        Meter ruler

·        Wire (3 meters)

·        Leads/connectors (x7)

·        Variable resistor

PLAN

1. Set up equipment
2. Attach the appropriate length of wire to the clips
3. Measure the current and voltage
4. Repeat this 2 or 3 times
5. Record data in a table
6. Calculate the resistance of the wire