The current is a measure of the charge that flows per second.
Current=charge/time
Since the charge on each electron is the same, the current represents the number of electrons flowing per second. If the resistance is high, the flow of electrons is slowed down and so the number of electrons per secon is reduced.is.the current is reduced.
Equiptment:
.ruler with wire attached
.wires and crocodile clips
.Power supply
.Voltmeter and Ammeter
The equipment should be set up like this:
Method:
1. Set all the equipment up as the diagram shows above
2. Turn the power onto 3 Volts
3. Using a crocodile clip and scan each of the measurements. Starting at 0cm and increasing the length by 10 untill you reach 100cm.
4. Read the voltage and the current off of the ammeter and the voltmeter, and record the results.
5. Find the resistance ( R=V )
I
Safety:
In order to preform a safe experiment, a low voltage of 3V was chosen so that overheating was minimalised. Furthermore, lengths lower than 10cm were not tried, which also helped to avoid overheating.
Variables:
. Independant variable: In this experiment, the independant variables is the length of the wire, the material and width of the wire and the starting temperature of the wire.
.Dependant Variable: In this experiment, the dependant variables is the voltage across the wire, the current in the circuit and the temperature of the wire throughout the experiment
Prediction:
My prediction is that the longer the wire, the higher the resistance is going to be because the longer the wire, the more times free electrons will collide with other free electrons. Therefore, more energy is going to be lost in these collisions (as heat)
Results:
TEST1:
TEST 2:
Results:
Evaluation:
As the results and graph quite clearly show, that when the length is increased the resistance also increases. Because i have tested this experiment twice, it is said for both wires not just one.
Both wires show a strong trend of a straight line. I.E the length of the wire is shown to be directly proportional to the resistance- double the lengths the resistance doubles.
Some of my measurements may not have been correct. This could have been due to a number of things:
The accurate measurement would not have been exact because the exact place where the crocodile clip would be is not visable to the human eye.
Connections could have been faulty and/or the heat could have effected measurements
And whilst extremly unlikely, it is concievable that the power supply was providing a different voltage for some results. This would not have affected the final results but the measurements could have been more accurate by using batteries
