In this investigation, we are investigating how the length of wire affects resistance current and voltage. We can change the size or number of cell(s), the length or thickness of the wire, and the length of the circuit. To do this, we will set up a circuit: A cell connected to an ammeter and a piece of wire in series, and a voltmeter connected outside the circuit (so that the voltage and current will not change due to their presence. For this experiment we will be using a 6V cell, wires to connect the circuit, an ammeter to measure current, a voltmeter to measure the voltage, and the wire we are measuring the resistance of (Constantine).
This means we will be measuring current (in amps) and voltage (in volts), from which we can work out the resistance (in ohms). The range of results we will be collecting will be from 1m to 10cm of wire, measuring every 10cm. The wire we will be measuring will be Constantine, since it conducts electricity well, and the resistance shouldn’t change due to temperature. To make sure it is a fair test, the wire will be strapped to the ruler tightly, we will be using the same circuit for all the tests, and the only thing we will be changing will be the length of wire.
We will also be repeating the experiment twice after to make sure there are no misfit results. We also conducted preliminary work on this investigation about thickness of wire. We found that when wire got much larger than 30 SWG it gets too hot and results cant be recorder properly (although this doesn’t apply to Constantine wire), and if too thin then results will be too hard to measure due to the small wire. Also, if the wire gets hot, energy is given off as heat, therefore resistance increases. Based on this information, I can now make a prediction. I predict that the longer the wire, the higher resistance will be.
This is because the longer the wire, the further the electrons have to travel, and the longer the wire, the more collisions there will be between the electrons in the wire and the wire atoms. This means energy would be given off as heat, increasing resistance. This is based on our preliminary work on how the thickness of wire affects resistance. Using our procedure of connecting the circuit, collecting relevant data and then repeating the process, we collected the relevant evidence: Current and voltage (also with the length of wire), from which we could work out resistance of the wire.
To work out resistance, we used the formula R = V/ I . This means Resistance equals voltage divided by current. The results are shown below: Test 1: Length Of Wire (cm) Voltage (V) Current (A) Resistance (Ohms)0 From this we worked out the average resistance of each length of wire (by adding all the resistance values for that length of wire and dividing by three): Length Of Wire (cm) Average Resistance (Ohms).
These results can now be plotted on a graph: From these tables and charts we can see a correlation. It is a positive correlation, meaning that as the length of wire increases so does the resistance. The correlation also appears to be directly proportional from X to Y, which means that there is an equal rate of increase in resistance. An example of this would 30 and 60 cm: the resistance in 30cm is 1. 50 ohms, and through 60cm of wire there is exactly 3.
00 ohms. This is directly proportional, since when the wire is doubled the resistance is too. The theory behind electricity and conduction supports this too: The longer the wire, the more atoms there are, The more atoms mean more collisions with electrons, so there is less flowing through, which makes for a higher resistance. An example of this would be if a 10cm wire had 8000 atoms, a 20cm length of that wire would have 16,000. If there were 800 collisions in the 10cm length of wire, there would be 1,600 in the 20cm length.
This conclusion supports and proves my prediction fully, as we can see from the graphs and results. Mostly the experiment was a success. We collected reliable data easily and quickly, without any problems. We had preliminary work to back up our data, conducted repeats and made sure it was a fair test. The evidence we have is good quality, was directly proportional to a good quality extent, but wasn’t totally accurate (most resistance values are a small amount of an ohm off direct proportion). The main anomaly appears to be the metre value, since the resistance is quite far under direct proportion.
It is . 11 under what it should be for 1M, and so are a few other values, this could be down to a battery not fully charged; it isn’t too inaccurate though. Our procedure was good too, but more repeats could have been done to make sure it was a fair test. On the other hand, more repeats could have made the data less accurate due to almost all the results being slightly inaccurate. The evidence we have collected is sufficient to support our theory, and although we do have one large anomaly and a few small ones, we also have a few perfect examples of direct proportion.
To provide extra evidence, more repeats could have been done, and an extra experiment on different types of wires, seeing how the material affects resistance. Overall it was a good and accurate experiment. Ralph Weatherburn 11T Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.