If the wire was thicker, electrons would have more space and would be free to move, therefore moving around the circuit faster.
Temperature effects the electrons. Electrons are given more energy in higher temperatures (activation energy). This makes it easier for them to flow and altogether reduces resistance.
The Material of the wire does affect resistance because different materials have different structures, some structures will increase resistance but some others have impurities, which decrease conductivity and increase resistance.
The resistance of the wire is proven by:
R = I Length
A Area of cross section
Resistivity of the metal
My Prediction
I predict that when I carry out my experiment into the resistance of wires, the longer the wire I use, the greater the level of resistance than on a shorter wire where the resistance will be less.
I also predict that the shorter and thicker the wire the less resistance there would be compared to that of a longer and thinner wire, where it would take longer for the electrons to flow around the circuit.
Preliminary Experiment
For my preliminary experiment I will be investigating the electrical resistance in a wire.
I will try and prove that my prediction is correct whilst carrying out my experiment.
Also, the purpose of the preliminary experiment is to find out about any pratical problems which will arise such as how to manage the lengths of the wire, the best way to measure their length and how to connect them into the circuit.
It will also be an investigation into deciding which lengths and thicknesses of wire to use in my Investigation, in order to get sensible results as it is no use changing the length by 10cm if the change in resistance is too small.
I will use several lengths and thicknesses of wire to help me plan my investigation in detail.
Method for Investigation
For my experiment I shall be using the following apparatus:
1 x Power pack
1 x Voltmeter (to measure volts)
1 x Ammeter (to measure ampres-current)
Crocadile clips
Variety of wire
Carboard tube (to wrap the wire around)
Resistor
I will measure the resistance of the wire in the circuit overleaf.
For my Investigation I will be measuring the resistance of the wire and trying to prove my prediction. I will use the apparatus listed. Once I have found the readings of volts and current from the ammeter and voltmeter, I will use the equation:
R = V
I
To find out the resistance of the wire.
I will use a variety of wires, different lengths and thicknesses to try and give me the correct conclusion and to prove what I said in my prediction.
I will record my results of the different lengths and thicknesses of the wires and list them in a table.
Once I have set up my circuit, with all the equipment in the right places I will add the wire and take a reading using the voltmeter and ammeter readings.
My results shall give me a better understanding of resistance in the wire and I will try to examine closely how to reduce resistance in a circuit with evidence from my results.
It is important that during my investigation I make it as fair and safe as possible.
I can therefore take into consideration the following points:
* I shall make sure that the power pack is turned on safely, when I have put everything else into the circuit, so that there is not a risk of being electricuted.
* Also I shall make sure that any liquids or substances that are nearby in the Scince lab are kept well away from the power pack.
* I shall keep the crocadile clips closed whilst not in the circuit as someone could be injured by them.
* Wrapping wire up when not in use is essential as someone could trip up from it if dropped on the floor or it could get tangled up and cause interruptions whilst carrying out my experiment.
* I will make sure that no equipment will fall of the table as it could be damaged and the test could end up not fair as volt meter or ammeter could be damaged
* I will carry out my experiments in the same temperature so that in each wire the electrons are in the same temperature, as the other wire, making the experiment fair as one does not benefit off more heat.
* I will also use the same power on every wire so that the amount of power is the same.
All of the reasons I have listed shall make the preliminary experiment as fair and as safe as possible.
My wires shall be measured and I will try to detect that the longer the wire, the higher the resistance.
Results.
As I have carried out my experiment successfully, a list of my results are below:
Investigation
As I have carried out my preliminary experiment successfully. I propose that for my actual investigation the lengths of my wires will be, 1m, 1.5m, 2m and 3m. The thicknesses will be 26swg, 28swg, and 30 swg.
I will make sure that this investigation is fair by recording the different readings and results of each piece of wire.
The wire will be made of the same material, also the wires will all be in the same temperature, room temperature.
It is important that this experiment is carried out accurately and precisely to give me the results that I am after.
Apparatus for Investigation
1 x Power pack
1 x Voltmeter (to measure volts)
1 x Ammeter (to measure ampres-current)
Crocadile clips
Wires
Carboard tube (to wrap the wire around)
Variable Resistor
Method
As I have now planned my experiment, I can draw up my method that I will use for my actual experiment:
- Set up Apparatus
- Set the power pack on as low a voltage as possible, so that there is not too high a voltage passing through the current.
- Place the 1m of wire between the 2 crocadile clips to complete the circuit if necessary wrap the wire around the carboard tube.
- Turn on the power pack and record the readings on the Ammeter and Voltmeter, remembering to turn off the power pack between the readings.
- Alter the variable resistor and take a second reading of 1 meter wire.
- Take 3 readings of current as each of the lengths
- Record readings in a table
- Work out the resistance using Ohms law: R = V
I
- Do this for both thicknesses of wire
- I will make my experiment fair by only changing one variable, in this case, length.
- I will keep all the other factors constant
- I will take 3 readings for each length in order to draw an accuartate conclusion at the end of the experiment.
- I will keep the voltage low, as it will cause high currents that will heat up the wires.
Results