I predict that if you increase the voltage, the magnets strength will increase and the magnetic field will get bigger, this is because Ohms law = V=IR, so if you increase the voltage, the current will increase. If the coil of wire has a resistance of 1 ohm and you pass volts through the wire, the wire will have a current of 6 amps. The second method that I predict which would affect the strength, is to place the coil around the nail. Also, if you increase the number of coils around the nail, this will also increase the strength of the magnet.
The magnet can affect the randomly arranged domains by arranging the domains in line. The stronger the magnet, the more domains will be affected and put in line making the iron a magnet. I also predict that if I double the current the magnetic field will double. i. e. The strength of the magnet will be directly proportional to the current. Method: Equipment: Power pack, compass, wire (for coil), nail (iron), ammeter, 2 crocodile clips, ruler, extended wires. Diagram: Set up the equipment as shown above.
Make sure the equipment is set up correctly and there is the right amount of coils on the piece of copper. Also make sure everything is working. Place the compass about a metre away from the coils. Turn the power supply on and increase the voltage until the ammeter reads 0. 1 Amps. Move the compass towards the coil of wire. Use your finger to do this. When the compass moves or makes a sudden turn stop applying force to it. Then measure the distance between the coil of wire and the compass. Record the result and repeat this 3 times.
After you have repeated this 3 times you change the current to 0. 2 Amps. You then do the same process for what you did for 0. 1 Amps, this makes the test fair. Results table: Size of the field (mm) Test number Current (Amperes, A) Conclusion: My results support part of hypothesis.
In my hypothesis I said that if I increase the current the magnetic field will increase, this is shown on my results table. The second part where my results support my hypothesis is that when a current passes through a coil of wire, it will become a magnet and when the current is stopped the coil of wire will become non-magnetic. Some parts of my results dont support my hypothesis, as I predicted that if I double the current the magnetic field would double. From my graph I can see at 0. 1 amps the field is 35, so if I were to double this I would get 70 but for 0.
2 amps I got 67. 33, so from this you can see that if I double the current the magnetic field does not double. The current is directly proportional to the magnetic field because it is a straight line. Evaluation: My results are reliable because I used the same equipment throughout the experiment. I also repeated my method 3 times, so I could get a fair average. I also made sure I kept the same number of coils of wire throughout the experiment. I also did the experiment in one day, therefore the room temperature was the same.
These are the reasons why my test was a fair test; therefore the results I got were reliable. There was a problem when I did the test. The problem is, when the current and resistance get too high, the circuit gets hot and then trips out. This can affect the results because when the circuit gets too hot, and the resistance gets higher, the current or p. d. that is passing through, will be less than what it should be, therefore the magnetic field will be smaller than what it should be, because of this the results will be different.
To solve this problem we might have to use thicker wire. We could also use shorter wire, Doing these would make the results more accurate. Another way we could solve the problem could be to let it cool down after it trips out. Another problem when doing this experiment is that the compass could be affected by the other groups magnetic field, this is because everyone was working at the same time. A way to solve this problem could be, to do the experiment at different times, like one after the other. Or you could do it in different rooms.