## Method- the voltage (measured in volts) and current

Method- To conduct this experiment I will firstly wrap 25 coils of wire around a soft iron core. I will then create a complete circuit with an ammeter in series and a voltmeter in parallel. As a variable I will be setting the voltage to 10 volts on the adjustable power supply, which means the current will also change, I will then turn the power on so the iron is magnetised and then try to pick up as many nails as possible with one dip of the now magnetic iron core into the pile of nails set out on the table.

I will then weigh the number of nails the iron electromagnetic picked up and record this result; I will then repeat this 3 times at the same voltage and current, and then change the voltage to 15,20,25,30,35 volts repeating all these 3 times to get an accurate result. By recording both the voltage (measured in volts) and current (measured in amps) of the voltmeter and ammeter, I will be able to work out how much power (measured in watts) is going through the wire and soft iron core, I can work this out by multiplying the current by the voltage. Equipment Adjustable power supply, low voltage, DC.

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Wire with plastic insulation Soft iron core- laminated Wire stripper Crocodile clips Complete circuit- using wires Voltmeter Ammeter Iron nails Weighting apparatus Diagram Prediction I predict that if I increase the voltage and current that passes through the wire and the soft iron core, it will in turn increase the power as voltage and current multiplied together equals the power, and this will then increase the magnetization of the soft iron core and it will pick up more nails. I predict this because the more electrical power u add the bigger the magnetic field, which then increases it’s strength.

Expected graph Key factors to vary I’m going to vary the voltage and current, which are multiplied together to get the power and how many watts are flowing through the circuit. Key factors to control The factors I am going to control are the number of coils and the same amount of insulating wire used to wrap around the soft iron core, this will be enough wire for 25 coils. I will use the same amount of iron nails and the same iron core for the whole investigation, I will also use the same wires used to connect the circuit to the power supply which I will also keep the same. Extent and range of evidence.

I am going to use 6 variables; 10, 15, 20, 25, 30, 35 volts. These measurements are recorded off the voltmeter, I will also record the current on the ammeter as I can then multiply the results together and get the power, and I will repeat these 3 times to make my results accurate. Precision and reliability of evidence I will make sure that my results are precise and reliable, by making sure that my voltmeter is in parallel and my ammeter is in series. I will be precise when wrapping the coils around the top of the soft iron core and to thoroughly insure that there are 25 coils.

I will also make sure that there is the same amount of nails each time and that those are in a pile with the same diameter each time. I will also make my results more accurate by repeating each different power total three times. Safety To make sure that my investigation is safe, I will not turn the voltage up too high as this will then rise the temperature of the soft iron core and the insulating wire will begin to burn, this could be dangerous as it also vibrates when hot. Scientific knowledge The passage of an electric current along a wire creates a magnetic field around the wire.

The fields are in the shape of a series of concentric rings. We can make use of this magnetic field by wrapping a wire carrying a current around a soft iron core. Soft iron is used because it is easily magnetised and demagnetised, so when the power is switched on the magnetic lines of force flow into the iron it becomes a magnet. The more coils of wire used in around the soft iron core, the stronger the magnet is. If there is one coil, and another is added, then the two coils have twice the strength of one.

The same as in if the current and voltage is increased going through the coils then the magnet will be stronger. The shape of the magnetic field is the same as a bar magnet. Diagram Relevant information from trials From my trials I completed in a previous lesson I found out that the best amount of coils to use is 25 as this gives the electromagnet enough strength to pick up enough nails when the voltage is set to 10 volts and its also not to many coils, so when the voltage is 35 the electromagnet wont get too hot and burn the insulating wire.