Our aim for this experiment is to find out a method of increasing the strength of an electromagnet. My aim for this experiment is to see if the number of turns in the coil around a nail can affect the strength of an electromagnet.
Whilst doing this experiment, we will need the following apparatus; an iron nail, a power pack, some wire to wrap around the nail, leads, crocodile clips, a variable resistor, and some paperclips.
The variables of this experiment, to change the strength of the magnet we could change the iron core; you can get soft iron and normal iron. You change the number of coils, change the current, or change the resistance, or change the thickness of the wire.
My partner and I chose to change the amount of coils around the nail, for our experiment.
‘Soft’ iron loses its magnetism very quickly when the current stops. Normal iron keeps its magnetism when the current stops.
There are also different methods, which we could use to test the magnetism of the electromagnet. We could either count the number of paperclips the magnet can pick up. We could weigh the amount of iron filings the magnet is able to pick up, we could measure the distance in which the magnet will start to attract a paperclip, or we could have calculated the force in Newton’s the magnet is able to pull, by using a Newton meter.
In my experiment I will be using paperclips. I will count the number of paperclips the magnet can pick up.
In my experiment my variables will be the amount of coils as it will be coiled around the nail and this number of coils will be varied at 10 coils then 20 coils then 30 coils then 40 coils then 50 coils then 60 then 70 and finally 80 coils. The current will be a constant so it will be the same all the way for a fair test it will be measured in amps. The size of the coil will always stay the same throughout the experiment, as we do not have extra facilities. The amount and size of the iron will star the same, as another constant-it will be a large nail, as we don’t have larger pieces of iron. I will use paperclips as the metal that the nail will pick up.
In our preliminary experiment we connected up the apparatus, roughly, like in the diagram below.
Our circuit looked roughly like this in our preliminary except we had connected an ammeter as well, in series with the power source.
To make my test fair and safe I will always use the same nail because some nails are bigger or smaller than others so some will pick up more paperclips than others, I will also use the same piece of wire because some wires can have extra copper wires than others causing more or extra paperclips being picked up. To make it more of a fair test I should keep the current exactly the same because more current can pick up more paperclips and less current will pick up fewer paperclips.
I predict that the more coils we add to the electromagnet, the stronger the magnetism will be and therefore the larger amount of paperclips the magnet will be able to suspend. So if you double the amount of coils, than the magnet will pick up double the amount of paperclips.
I predict that when the more coils are added to the iron nail then the more paper clips that the nail will attract as each turn will produce a certain strength or a magnetic field. As the more the turns the stronger the magnetic field would be. Will show my prediction in a graph.
Here the y-axis represents the amount of paperclips that are attracted, and the x-axis is the amount of coils around the iron nail and it shows a steady increase in the attraction of the paperclips. I.e. number of paper clips is directionally proportional to the number of turns.
The reason for the sudden vertical direction of the line is because at an extent the magnetism will stop increasing. Although I do not think that my final graph will look like my prediction graph because I don’t think I would have magnetised it to that extent. To fully magnetise the magnet you would have had to put a few hundred coils around the core, where as I am only going up to eighty. So my graph would look more or less like this.
Obtaining My Evidence
In our preliminary experiment I connected up the apparatus, after gathering them together, as shown in the diagram below.
Whilst we were doing the preliminary I noticed that the power pack kept on blowing and so I decided to fix this by using a variable resistor in the secondary experiment, so that we could control the current.
The reason why the power pack kept on blowing was because the power pack, for safety reasons could only hold four amps, so if there was more then four amps then it would cut the supply to the circuit. Therefore we need a variable resistor to make the current flow.