Current In The Experiment example essay topic

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 become much stronger, until you were to reach a state where you had aligned all the possible domains up.

A fully magnetized 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 6 A to 0.5 A. 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 dis cluded 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 current goes up, the strength of the electromagnet goes up directly proportionate to it. In section C, all of the domains had lined up. Section C was not drawn in on my graph because of the fact that there was not enough of a wide range of readings available to be taken with the apparatus that I was given.

The graph was not what we had expected, as I wrote in my planning that I was expecting to be drawing a straight line graph. This prediction was wrong because we had not expected the domains to take time to line up. We thought that they would line up straight away. Evaluating Evidence In the experiment, the current changed quicker as it increased per centimeter we pushed the variable resistor. This made it fluctuate more, and it was therefore harder to be able to obtain accurate readings. After we had been carrying out the experiment for a while, the bar may have retained a bit of magnetism if a large enough current was put through.

There was also a change in the temperature of the bar-it heated up. When doing the experiment we made sure that we turned it off after taking each reading so as we kept control of the temperature in the experiment and to avoid it heating up and affecting the experiment, making it unfair. There was less chance of getting an anomaly in the experiment because we took an average of the three results. It was a reasonably accurate experiment, and if I repeated it I would get similar results.

I can justify all but the third section on my graph (C) because I didn|t go to a high enough voltage, but if I did I would have obtained the SS leveling off zone because other people using a high enough voltage did. If I wanted to make some improvements to the experiment, I would take the results five times, and to a greater degree of accuracy of current and weight loss (four decimal places or more). We also could have tried to keep the temperature more constant by not leaving the current on between the takings of readings and leaving it to cool. We should also have zeroed the balance before taking each reading. To extend the investigation I could have tried varying the number of coils, or another factor, keeping the current constant, then another variable and comparing the results of varying those others. I could also have tried using iron filings for an example to see if different results were given.

Bibliography

Books that I have used for help are: A new and physics by D. Bryant and D.E. Kershaw also Advanced physics fields, waves and atoms by T. Duncan..