Resistance of a Wire
Aim
Which factors affect the resistance of a wire?
Prediction
I believe the factors which affect the resistance of a wire are:
1. The length- the increase in length could increase the resistance.
2. The thickness of the core.
3. The material of which the wire is made up of- e.g. Copper,
constantan and nichrone.
4. The number of strands within a wire:
5. The amount of current flowing through the wire.
For this experiment, the factors which will be tested and measured
will be the length of the wire, the material of which the wire is made
from to see whether it affects the resistance, and seeing whether the
variable resistor also affects the wire in any way.
Apparatus
* Power pack
* 9 strands of copper wire, 0.193 mm thick, 30 cm long.
* 9 strands of nichrone wire, 0.193 mm thick, 30 cm long.
* 9 strands of constantan wire, 0.193 mm thick, 30 cm long.
* Ammeter, 10 amps max.
* Voltmeter, 20 volts max.
* Variable resister
* Heat proof matt.
* 7 wire leads.
* 2 crocodile clips.
* Ruler.
* Scissors.
Diagram:
Method
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Firstly collect all the apparatus needed to complete the investigation
and set the right apparatus into the correct positions.
Start of by measuring the volts and amps of one of the wires at a low
resistance, whilst always keeping the current the same for each time
at 6v. This wire should be 30 cm to start of with. When the volts and
amps have been measured, switch off the power pack between each
measurement so that the current is cut off. When this is done, cut off
5 cm of the wire and measure the volts and amps of the now 15 cm long
All of the sources of current to the equipment should be isolated and signs need to be fixed to ensure that the nature of the equipment is known
equation V = IR. V - volts, I - current and R - resistance. I plotted
it to a 5V power supply as a more convenient way of measure. As the
You can make an electric current in a wire if a wire is at right
Ø I read from the ammeter each time I cut down the length by using
the nail. We then switched on the power supply and set the voltage to 4 V. We tested the number of paper clips the nail would pick up, each. time turning the power supply off and winding the coil five more times.
I also decided to use a wooden block to keep hold of the wire, because
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