Apparatus:
- A voltmeter
- An ammeter
- One metre of nichrome wire
- Two crocodile clips
- Five wires
- A single cell
- One 1m ruler
Method:
- Collect the apparatus
- Set up the apparatus as shown:
- Set the voltage on the single cell to as low as possible, as to avoid the wire burning out
- Place the metre of nichrome wire against a metre ruler
- Complete the circuit by placing the crocodile clips at each end of the metre of nichrome wire
- Turn on the single cell and record what the ammeter and voltmeter read
- Keep the first crocodile clip at one end of the wire, and set the second crocodile clip at 90cm. Turn on the single cell, and record the ammeter and voltmeter readings
- Keep the first crocodile clip at one end of the wire, and set the second crocodile clip at 80cm. Repeat the test
- Repeat this experiment for every 10cm of nichrome wire, until the second crocodile clip reaches 10cm
- Once you’ve completed the series of tests down to 10 cm of wire, work out the resistance for all the results using Ohm’s law – R = V / I
- Record the results in a table, then transfer the results onto a graph
Results:
Preliminary experiment test results:
From looking at these preliminary experiment test results, I can determine that I have set up my apparatus correctly and that there are no outliers or unusual results.
Main experiment test results:
Analysis:
This experiment has proved that my hypothesis was correct. As the length of the wire increased, the resistance of the wire also increased. This is because as the wire gets longer, more and more electrons have to travel down to the positive end and they have longer to travel. This results in a greater possibility of an electron colliding with an atom, causing resistance.
Evaluation:
These results are not completely accurate as I was only using a ruler to measure the length of the wire, so the measurements may have varied. In addition, the voltmeter could only read to one decimal place, so the results are not as precise as they could be.
However, after looking at my main experiment test results, I can conclude that they are quite reliable as they are very similar to my preliminary experiment test results. Also, I didn’t find any outliers.
If I had to redo this experiment, I would use a more effective way of measuring the length of the wire. Attaching the wire to a ruler does not seem to me to be the most efficient way of conducting the experiment. Furthermore, I would use a smaller-scale voltmeter so that my readings would be more specific.
