What is resistance?
Resistance is anything that reduces the current in a circuit. It is measured in OHMS, Ω
What is current?
Current is the flow of electrons around a circuit. This is measured in Amps.
What is voltage?
Voltage is the driving force that pushes electrons around a circuit. It is measured in volts.
What is OHMS Law?
OHMS Law states the relation between voltage, current, and resistance. The law does not apply when heat is involved. The formulae are as follows.
V= I x R
I= V ÷ R
R= V ÷ I
Prediction
If we increase the surface area the resistance will decrease. For example, if you double the cross-sectional area the resistance will be halved.
A diagram of the apparatus
Fair Test
Throughout the investigation each of the following will be kept constant:
-Temperature - 21ºC
-Length of wire - 117 cm
-Material - Solder wire
Number of Measurements
I plan to investigate how the resistance varies with solder wire. I will repeat the readings and then calculate the average reading for each wire.
The readings
I took readings three times and then calculated the mean average. Cm’s refers to how far from the left the crocodile clip is.
Analysis
My Prediction was that if we increase the surface area the resistance will decrease.
The previous calculations which I have done throughout this investigation support my prediction which is consistent with my background theory: If we double the diameter of a wire of given length the cross-sectional area increases 4 times. So the applied voltage will be able to affect 4 times the number of electrons, i.e. the current increases and the resistance decreases.
The scatter-graph.
The vertical part is in Volts and the horizontal part is in Cm’s.
This graph shows a straight-line correlation between cm’s and volts.
What is the resistance of the wire?
Resistance Volts ÷ Amps
Resistance 2.99 ÷ 0.58
Resistance 5.16Ω
Are my results accurate?
I don’t think my measurements will be very accurate because it did no have an accurate measure of centimetres. Also the crocodile clip covered 0.5cm’s and the wire was not tight.
The volts and amps were accurate to 2 decimal places.
