Magnets were formed when certain molten metals, (iron, nickel and cobalt,) cool. Normally when the atoms in a non-magnetic crystallise, the atoms point in random directions. But because of the properties of the metals mentioned, these atoms line up into parts of the magnetic with similar directions called domains. This is because the earth has a magnetic field, and the atoms in the metal all follow these magnetic lines and form these domains. This is similar to what happens when an electromagnet is formed.
Prediction
I think that the more current that goes through the wire, the greater the electromagnetic pull of the soft-iron core will be. This is because the current going through the wire makes the soft-iron core is the factor that induces electromagnetism, as so when there is more current, there will be more electromagnetism. This is the same with the number of coils, used with the electromagnet, the more power is returned. The return and investment are not directly proportional. I think this because of the aforementioned scientific knowledge.
Aim
In this experiment we want to test the power of an electromagnet when the:
-Numbers of coils are varied
-When the amount of current is varied
Preliminary Experiment
In this experiment we experimented with different ways of testing the strength of the electromagnet. We also discovered which was the best core to use, how many coils to use, when the wire melted, and which was the best current to use. We did this by setting up the experiment as shown below and then changing different factors in it, such as the core and number of coils.
Apparatus
Electromagnet.
Crocodile 2.5 M Wire Ammeter
Small Yellow Connector wire. Power Pack
Soft Iron Core
Method
1) A 2.5 m electrical wire will be coiled around a soft-iron core 30 times.
2) Crocodile clips will be connected to yellow connecting wires at each end.
3) These together with the ammeter will be connected up to the power supply as shown in the circuit diagram.
4) A fixed amount of iron filings will be poured over the electromagnet with the power switched on.
5) The wire will be shaken until no more iron filings come off.
6) The power will be turned off. All of the iron filings that drop off will be weighed.
I will vary only the current in this experiment. All other factors will be kept constant. I will measure the amount of iron filings at 1,2,3,4 & 5 amps. I will repeat each experiment three times for accuracy.
Safety Precautions
We will make sure that there is no bare insulation or any water near any electrical equipment to prevent electrocution.
Conclusion
The Scientific Explanation
As the current is passed on to the wire, it becomes a magnet itself, in accordance with the right hand rule. It magnetises the substance at the core. Inside the substance there are domains. When they are magnetised they aligned themselves onto the same direction, making it magnetic, this needs energy to perform and maintain the process, and it is not cumulative so the more energy put into it the more will come out.