Apparatus
- Stand and clamp
- Power supply
- Iron core
- Iron nail
- Weights (5g, 10g, 100g)
- Ammeter
- Variable resistor
I predict that the more current there is through the circuit, the more powerful the magnetic field will be, and therefore the more weight the nail will support. I think this will happen because I know that when a current is flowing through a wire a magnetic field is created. Also the strength of the current is directly proportional to the strength of the magnetic field e.g. if the current doubles so will the magnetic field strength. So if there is more current flowing in the wire, the magnetic field will be greater than also.
In this experiment the wire magnetises the core, so with increased current in the wire the core should become more magnetised and be able to support a greater mass.
While doing this experiment I will record the following measurements:
- The current flowing in the circuit over a 5A span (0-5A)
- The mass that the magnet can hold (from when the nail drops)
- The number of turns on the coil
Preliminary results
Note: Iron nail weighs 13.4g
By doing these preliminary results I determined that I will defiantly be using a wider range of results in the proper experiment (current 0-5A). I also determined that the number of coils I used (30) was suitable for the experiment. I also learned the best way of doing the experiment so I get the most accurate results.
Proper experiment results 1
Note: Iron nail weighs 13.4g
Proper experiment results 2
Note: Iron nail weighs 13.4g
You can see that from the graphs that the mass and current are proportional, you can tell this because the points on the graph go up in a smooth curve. Also the line of best fit is showing a strong positive correlation between the current and mass, meaning that the two are directly proportional. This is exactly as I predicted in my plan, I stated that because the current and mass held are directly proportional, the more current that would be flowing through circuit the more powerful the magnet would be and therefore that more mass would be held.
I made this prediction based on what I know about current and magnetic fields. When there is a current flowing through a wire a magnetic field is created around the wire, and so when there is a stronger current flowing through the wire there is a stronger magnetic field around the wire. This theory has been proved in the experiment I performed.
I think that the results I obtained are quite accurate, I can see this best looking at the graph. The points on the first graph are quite close to the line of best fit, but a few are a bit too far away to be called very accurate.
The second graph shows much more accurate results with nearly all the points being very close to the line of best-fit, i.e. there is not a large scatter of the points.
I think these results are good enough to prove the theory that current and the strength of the magnetic field around it are proportional. I think this is the case as the results I obtained were more or less what I expected to obtain.
There are a couple of results that I obtained which look slightly out of sync with the rest of the results I got, I don’t think they are so drastically wrong that I can call them anomalies but they seem to be a little bit off.
In the first set of results I obtained a mass held of 113.4g at 2.5A, when you see this on the graph it looks too low. I believe this could be a slight fault with the way this result. It became apparent while I was taking the results that the nail is not always as magnetised as it could or should be. This sometimes resulted in the weights and nail falling off at clearly incorrect readings. Normally I took the reading again if it looked about 100g off what it should have been, but sometimes the weights will have dropped at a reading that doesn’t at first look incorrect. This is what I believe happened with the aforementioned result.
I think that the method I used was on the whole a good, efficient and reliable one. I think this because my results were quite accurate. I don’t believe that there was anything I could change to make the method any more accurate.
If I had more time to continue my investigation I could carry out some extra work to further it.
I could do another experiment which uses a similar method to demonstrate the effect on the magnetic field around a wire whilst a current is flowing through it.
A wire is coiled round an iron nail as before and set up in a circuit much similar to the one I used. A current is then passed through the circuit and wire, magnetising the nail. I would then place the nail over a pile of iron filings and the filings should stick to the nail. I would vary the current and the number of coils and see how the amount of filings attracted to the nail varies when the aforementioned factors are changed. This should give me a good idea of how the current and magnetic field around that current are directly proportional.