Find out the factors affecting the strength of an electromagnet.

ELECTROMAGNETISM

AIM: The aim of this investigation is to find out the factors affecting the strength of an electromagnet.

BACKGROUND KNOWLEDGE (THEORY):

Magnetism is the tendency a metal such as iron, steel and cobalt have to attract other metals e.g. pins.

Magnetism arises as a result of the motion of charged particles called electrons in the wire. In most substances the effect of this motion cancel out, but in ferromagnetic substances they do not.

When insulated wire is wrapped round an iron nail and the ends of the wire are connected to a battery, and the nail becomes capable of picking up iron filing or paper clip. The nail is magnetised by the current in the wire. If the battery is disconnected then the clips will fall of. This is because they are not a permanent magnet; they are called temporary magnetism.

The iron filings cluster around the end of a magnet because a magnet behaves as if all its magnetism were concentrated near its ends.

These place were the magnetism appear to be concentrated are called the poles of the magnet.

INDUCED MAGNETISM (1)

IF a piece of ferromagnetic substance is made to touch or brought near to the pole of a magnet, it becomes a magnet itself. This is called induced magnetism.

This end of the substances nearest to the inducing pole has an opposite pole inducing in it. A chain of pin can be attached to a bar magnet, with each induced pole inducing and opposite pole next to it.

If the South Pole of a magnet is brought near the bottom of the lowest pin in fig1.2, the pin will be repelled showing it is a South Pole.

THE FACTORS AFFECTING MAGNETISM STRENGTH

I will try to use scientific theories and explanations wherever possible. I will try and get a valid set of results that I can use to draw a firm conclusion from and to backup my prediction.

Here is list of all the factors, which could affect my investigation. They are:

Current
Numbers of coils in the wire
Using a soft iron core
Placing an iron or steel core inside of the coil.

...

This is a preview of the whole essay

THE FACTORS AFFECTING MAGNETISM STRENGTH

I will try to use scientific theories and explanations wherever possible. I will try and get a valid set of results that I can use to draw a firm conclusion from and to backup my prediction.

Here is list of all the factors, which could affect my investigation. They are:

Current
Numbers of coils in the wire
Using a soft iron core
Placing an iron or steel core inside of the coil.

(INVESTIGATION)

In my investigation they’re five key factors, which I could change, but I am only going to change one of them. The variable that I am going to change is the current because I feel this is the easiest and most obvious one to do.

I predict, if I increase the current going through the coils of wire, the area coved by the magnetic field will increase and the nail will be able to pick up more paperclips.

The things that control the magnetism of an object are called Domains. These can be explained as a small area of magnetism inside a magnet. When an object is not magnetised the domains point in all random directions and cancel each other out. When it becomes magnetised the domains all go in one direction. When the current is turned on it will make all the domains point in one direction.

Apparatus:

Nail, Ammeter, Wires, Lab-Pack, and Paperclips.

Diagram

Method

To get meaningful and fairly accurate results I took the average from two results. The reading was taken from between 0.10 Amps and 1.00 Amps (went up in even Numbers), so I had a sufficient range to find any patterns or trends.

I repeated my results five times with different numbers of coils each time just to backup any patterns.

For safety I used a thin black wire , which I think is better because it could allow more current going through it with out burning up. After I had took a reading I turned the Lab-Pack of each time so the nail would not get too hot to handle.

Fair Test

The variable that I changed is the currant through the wire and the numbers of coils of the wire.

The variable, which I kept the same to ensure a fair test are:

length of nail
surface area of nail head.

The thing that I will measure is the amount of paperclips that the head of the nail picks up when magnetised. The weight of a paperclip was 0.5g. I used only the paperclips, which weighed 0.5g to ensure it was fair test.

Conclusion

In my investigation I found out that as I increased the current the amount of paperclips picked up had increased and as the number of coils decreased the number of paperclips picked up decreased.

You can find this evidence in all my results. My results are not exact because I had to take an average because I got different numbers of paperclips picked each time and I could not get it to the exact current that I wanted because it kept on changing.

In my results you can see, for 14 coils of wire as the current goes up the number of paperclips picked up increases.

Currant (amps) 14 Coils of Wire

2 4.6

4 11

6 14.6

8 22

10 25

12 35

14 40

The quote from my table above can backup my prediction and shows a pattern, that when the current is increased the number of paperclips picked up increases.

The conclusion that I can draw from this evidence is that when the current is increased the number of paperclips picked up increases because there is a stronger magnetic field around the magnet because the domains in side the iron are all pointing in one direction.

Evaluation

I think that I collected enough data in my investigation to draw affirm conclusion from. I took 5 readings of 9 nine different amounts of coils of wire, and they all showed that if the current was increased then the amount of paper clips picked up increased as well.

I think that I did the investigation as accurately as I could have, with the type of equipment that I had to use. I did get a few freakish results maybe because there were a few paperclips in there which wasn't suppose to be in there e.g. instead of being 0.5g there were some paperclips which were 0.7g, 0.2g, or even 1.0g which would have affected the weight the nail was picking up. Another reason could be the current because I could never get the current hit on what I wanted. E.g. it would always alternate between 0.09 amps and 0.99 amps if I wanted either 0.10 amp or 1.00 amps but I don't think that would have made much of a difference.

I also thought that when I decreased the number of coils the number of paperclips would decrease.

To improve the reliability of this experiment I took and average to cancel any freakish results, but there were sill some their. After every reading for each number of coils, I hit the nail on the table, which made it lose its magnetism. So it was fair on the next number of coils.

Current 60Coils, 55 Coils, 50 Coils,45 Coils, 40Coils, est.

2 4.6 6.3 5 6.3 4.3

6 14.6 14.6 17.3 15.3 14.6

12 35 25.3 30.3 22.3 21

When I went across the table as above I found quite a lot of freakish results. For 5.00 amps as the number of coils decreased the number of paperclips started to increase instead of decreasing.

I think that the results are quite reliable because they all support a pattern and I did collect sufficient evidence to support my conclusion.

If I had to do this investigation again then I would improve it by going only up to 10 amps for safety reasons and I take more care when I was measuring the weight of the paperclips so I wouldn't get any odd ones that should not be there.

I could use something which gave me more accurate readings of the currents flowing through the wire and a power pack which didn't give slight changes in the current given out and would be more steady.

To improve the reliability of this investigation I would change the way in which I did my experiment because I found it to be a little unreliable as in the table above. To improve the reliability I would put the paper clips on a top-pan balance and put the electromagnet at a certain height and calculate the decreases of weight on the top-pan balance to the strength of the electromagnet. I would take a range of readings from certain heights and take an average for each one. If a possible trend appears I could prove the trend by repeating the experiment with a different amount of current passing though the electromagnet.

The diagram shows how I will set up the apparatus for the experiment.

The electromagnet will attract the paperclips and there will be a change in weight on the top pan balance and I can use that to see how current effects the strength of magnetism.

BY: SYLVIA E. IFIDON

(29-11-2001).