Electromagnets - an investigation on electromagnets, our aim will be to find out what effects the strength of an electromagnet and how it affects it.

My Prediction

We all know that a wire carrying a current will produce a magnetic field around it self.  This means that if the wire is compressed or coiled into a solenoid then the field will be more compact and therefore very much stronger.  So, if more of the wire is wrapped around the iron bar then the electromagnet should become much stronger and stronger each time.

Also if we know that electric current is a movement of electrons and the more energy they have, the greater their velocity.  Hence, if the current is increased the magnetic field around the wire should also increase, thus producing a stronger electromagnet.

The Plan

To proceed with this investigation we will be requiring the following apparatus:

1. Thin conducting, insulated wire
2. Soft Iron core
3. Transformer
4. Ammeter
5. Variable resistor
6. Clamp stand
7. Paper clips

To ensure that the experiment will be fair, we will perform the experiments with the following rules

1. Conducting wire and iron core will be of the same size in both experiments
2. Size of paper clips will be the same in both experiments
3. In experiment 1 the number of turns will remain constant
4. In experiment 2 the amount of current will remain the same for each number of turns

We will also be performing each experiment three times to ensure accuracy of results so that we can produce an average result.

The things that we will be changing for each experiment are as follows:

1. The current rate in practical 1
2. The number of turns of wire in practical 2
3. The strength of the electromagnet
4. The amount of paper clips picked up

The Method

1. First I will get the iron core and wrap the insulated wire around it 40 times so that it looks like a solenoid.
2. Then I will connect the wire ends to the transformer and ammeter.
3. I will set the current to 1 amp for the start of the experiments and for the last experiment it will be set to 1 amp all the way through.
4. We then switch on the power and the iron core becomes magnetised.
5. Then we hold the electromagnet close to the pins that are laid on the table.
6.  As the pins are attracted and stuck onto the magnet we will count them and record them in a table
7. I will then increase the current by 0.5 amps until I reach 4 amps, recording the results every time I increase it by the 0.5 amps.
8. We will then do the experiment No. 2 keeping the current the same (set at 1 amp)  and set the turns to 20
9. I will attempt to pick up pins, record results and repeat for every time I add an extra 20 turns.  I will do this until I reach 140.

The Results

We successfully completed the experiment and to show this here are two table containing our results:

Experiment 1

Experiment 2

With these results that I have gained, I can create an average results set so that I can show the average results in a graph with a line of best fit going through it.  These graphs can be viewed on the next two pages.

The Conclusion

After completing the experiment we found that as you increase the current of an electromagnet, the strength does increases each time you add more current.  We found this out because in the experiment every time we increased the current rate we noticed that more pins were being picked up so we thought it that the increase in current does actually increase the strength of the electromagnet.  This is due to more energy given to the electrons and more velocity.

Also in the experiment no. 2 we said that each time you wrap more wire around the iron core the force field around it gets much stronger making the electromagnet stronger too.  We found this out because every time we wrapped more wire around the iron core, the amount of pins picked up increased.  This is due to the force field becoming much more compressed.

So after completing the investigation we have found that the increase of current and increase of wire wrapped around it strengthen electromagnets.  This means that our prediction was after all right.

The Evaluation

At the end I think that the investigation has worked out quit well and we received the results that we expected.  I predicted that the strength of a electromagnets increase when you either wrap more wire around it or increase the current flowing through it and after performing the investigation I have found that I was right all along.

The results were in fact adequate enough to bring us to a firm conclusion.  But even though my prediction was right we still received results that were not quite expected.  This is due to the errors that were made in recording the results.  We did not record the results properly because there were either pins hanging off or linked together.

We can improve the investigation by performing each experiment five times rather than the three to make it even fairer.  As well as being fair the investigation will gain us very accurate results to show.  We could also improve the investigation by using various types of core and various conducting wire (different diameters).  To detect the actual strength of the electromagnet I could have used a compass.