Investigate the strength of an electromagnet

TASK:

Investigate the strength of an electromagnet.

EQUIPMENT:

Battery : to give the electrons a push and supply the power.

Ammetre : to measure current flowing through the component (in amps)

Electromagnet : to measure its strength and see if it connects with the amount of coils wrapped around it.

Variable Resistor : to control the amount the electrical energy flowing through the circuit. It will be used as a safety device as it can make sure that the current does not exceed 3 amps. This is because the wire can get hot and this is not safe. It will also effect our results if the wire gets hot.

Switch : Control flow of electrons. It is also a safety device to stop the current flowing unnecessarily.

METHOD:

First we will set up the circuit as shown above wrapping ten coils around the electromagnet as this is the minimum number of coils we are going to use.
Place 100 staples in your hand and hold it out with a distance of 3cm in between your hand and the electromagnet.
Switch on the voltage of the power pack to 3v.
Switch on the ammeter and switch.
Remove your hand so there are staples hanging from the electromagnet.
Check the ammeter and make observations before removing your hand from the switch.
Record results.
Take the staples and count them and record results.
Repeat this procedure ten times in exactly the same way but each time increasing the number of coils wrapped around the electromagnet by ten (e.g: 10, 20, 30, 50 ……..)

INDEPENDENT VARIABLE:

The number of coils wrapped around the electromagnet. (increase by ten)

DEPENDANT VARIABLE:

The number of staples picked up; therefore determining the strength of electromagnet.

FAIR TESTING:

Same voltage on power pack (3volts.) This is because if the voltage is not the same the results will be affected as a higher voltage means more staples picked up as there is a larger magnetic field
Same size of staples; as the electromagnet may pick up many small staples and only a couple of big ones.
Same amount of staples held out. ...

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INDEPENDENT VARIABLE:

The number of coils wrapped around the electromagnet. (increase by ten)

DEPENDANT VARIABLE:

The number of staples picked up; therefore determining the strength of electromagnet.

FAIR TESTING:

Same voltage on power pack (3volts.) This is because if the voltage is not the same the results will be affected as a higher voltage means more staples picked up as there is a larger magnetic field
Same size of staples; as the electromagnet may pick up many small staples and only a couple of big ones.
Same amount of staples held out.
Same electromagnet. i.e size etc. as larger electromagnet may mean stronger therefore larger magnetic field.
Same wire. i.e strength, thickness, and length
Same distance between hand with staples and electromagnet. As the further away the hand is to the electromagnet the less it will pick up making inaccurate results.

SAFETY:

We will have a variable resistor in the circuit to make sure that the ammeter reading does not go over 3 amps which may cause it to heat up and this is dangerous
We will have a switch so that the flow of electrons is controlled and the wires do not heat up. This will also mean that the circuit will only be used when necessary.

PREDICTION:

My prediction is that as the number of coils increase so does the number of staples picked up therefore increasing the strength of the electromagnet. This is because as you increase the number of coils wrapped around the core you also increase the magnetic force around the coil.

PRELIMINARY DECISIONS:

The first thing we needed to decide was what the electromagnet would be picking up. We had a choice of many things e.g staples, nails, paperclips. We decided to use staples, the main reason being that they are small. This will mean that our results will have a distinct difference as if we were using nails the electromagnet may only be able to pick up one nail using 10 coils and one nail using 20 coils, this will make the results unclear. With staples as they are small they will be clear and precise in showing how the strength of the electromagnet changes.

The second thing we had to decide on was what voltage on the power pack we were using. We decided to use 3 volts as we needed a relatively low voltage which could prevent the wire getting hot but a voltage that could still pick up staples which showed distinct difference each time. 3 volts is the lowest voltage on the power pack and we found that it still picked up quite a lot: when using 40 coils it picked up 40 staples and when using 30 coils it picked up 33 staples. We found this to be quite a good result so we are using 3 volts.

ANALYSIS AND DRAWING CONCLUSION:

From my graph I can see that as I increased the number of coils, the electromagnet picked up more nails. This means that the strength of the electromagnet was increasing as the number of coils increased. My graph can tell me that there was a steady increase and my results table also tells me this. My average results also show a steady increase each time the number of coils is increased. I can see that with 10 coils wrapped around the iron core, only 3 nails were picked up and with 100 coils wrapped around the iron core 20 nails were picked up. Here, there is an obvious increase.

My graph shows that my line of best fit doesn’t pass through the origin, but it came quite close. This may be because the iron core is magnetised anyway and was acting as a magnet even before coils were added. This proves that when coils are added the magnet becomes stronger as the line of best fit increased as the number of coils increased. This can also prove that my line of best fit is fairly precise.

Also, by looking at my graph I can confirm that my results match my prediction; I predicted that as the number of coils increase, the number of nails attracted to the iron core will also increase. I expected this result as when an electrical current flows through the wire, the iron core becomes magnetised. This is because when the wire has an electrical current running through it a magnetic field is created around the wire, wrapping more wire around the coil concentrates and increases the magnetic field. Therefore, more nails are attracted to the iron core. If there is less coils wrapped around the iron core there will be a smaller magnetic field and less nails will be attracted.

I believe that the scientific reasoning in my prediction matches the reasoning of the actual test as I said that more coils will mean larger magnetic field and consequently more nails are picked up. This is what happened and as more wire was wrapped around the iron core, the magnetic field became stronger and more nails were picked up.

I think that my conclusion is firm in showing a trend, so is my graph as I now know the general rule. Unfortunately, it is not very firm in showing the exact increase and decrease of strength as the number of coils increase and decrease. However, I did manage to observe that the average results were increasing by about 2-3 each time, but there is no exact constant increase.

Finally, I can say that I am fairly happy with my results as I have successfully ‘investigated the strength of an electromagnet’ even though they are not brilliantly precise.

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