The Strength Of An Electromagnet Essay Research

The Strength Of An Electromagnet Essay, Research Paper

The strength of an Electromagnet

Planning Experimental procedures

"h The quantity that I am intending to investigate in my experiment

is the

strength of the electromagnet

"h The factors that affect the strength of an electromagnet are: The

temperature, current, length of the core, diameter, the thickness of the

wire used for the coils, how tightly the coils of wire are wrapped around,

the material and also the number of turns on the electromagnet.

"h I am only going to vary current in the experiment, all the other

factors

I will keep constant

"h I have chosen to vary current because, the more turns there are, the

more

powerful the magnet becomes and therefore the more domains there are. The

thicker the diameter is, the more domains there are in the middle and

therefore the stronger the electromagnet becomes.

The higher the temperature is, the easier it is for the domains to be able

to turn and line up. If you use a thinner wire it will cause more resistance

in the experiment. All of these factors will change the strength of the

electromagnet.

"h I decided to do current, as the others were more difficult to do

"h I believe that when I do the experiment, proportionally as the

current

increases, the strength will increase.

Force (N)

Current (A)

"h I have made this prediction because as you increase the current, you

will

induce more domains to line up- and if its proportional, you would then

double your current which would therefore double the domains (force). If you

were to cut a magnet in half, it doesn¡¦t destroy it, in actual fact two

magnets are created.

If you wanted, you could continue cutting the magnets in half each time

therefore making the magnets smaller and smaller. In theory, if we used an

extremely sharp, but still small blade, we would be able to on cutting

magnets in half until we reached a limit-this would be called a domain and

is about 1/1000th mm long and would consist of about 10 thousand million

atoms.

An unmagnetised iron would look like this:

Using the current in the coils, you would be able to re-align some of

the

domains. If you did this and as a result more of the domains were pointing

in the same direction, then the iron would have become a weak magnet.

A weak magnet would look like this:

When you switch off the current, the domains would return back to a random

set up. Obviously, if you were to line more domains up, the magnet would

bcome much stronger, until you were to reach a state where you had aligned

all the possible domains up.

A fully magnetised magnet would look like this:

"h Apparatus used: An electromagnet, powerpack, variable resistor,

ammeter,

an iron bar and an electric balance. The following diagram is how we set the

experiment up:

"h To measure the strength of the electromagnet, first of all we had to

weigh the iron bar. We then switched the current on to flow through the

circuit. By taking a range of different readings off both the balance and

the ammeter, we established that as you increased the amount of current, the

iron bar got lighter. This is because the electromagnet was getting

stronger, pulling the iron bar up and taking the pressure off from the

electric balance.

"h First of all I will set up the apparatus as planned, and I will take

readings ranging from 6A to 0.5A. Then checking the variation in the weight

of the iron bar. I did some preliminary experiments so that I could find out

the range of the current, and how much voltage was needed in the experiment,

and also exactly how far the electromagnet should be away from the iron bar.

"h I did a preliminary experiment before the actual experiment

"h I tested what was a safe current. I found out that a current up to

six

amps was satisfactory. We also tested what was a safe distance for an

electromagnet from the iron bar-ten centimeters was too far, two centimeters

was too close, five centimeters was a satisfactory distance.

Analysing Evidence & Drawing conclusions

To draw a conclusion from my graph, first of all I would divide it into

three

sections: Section A (the bottom), section B (the middle) and section C (the

top). This

would now make it easier to describe.

The first section (A) looks like it does because for the amount of current

put in, only

a few of the domains had lined up.

My second reading that I took was inaccurate, so on my graph I have circled

it, and discluded it in the drawing of the curve. The graph then gets

steeper (section

B), this is because all of the domains are now lining up. As the strength of

the

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