Investigation into the factors affecting the strength of electromagnets - Planning Experimental Procedures.

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INVESTIGATION INTO THE FACTORS AFFECTING THE STRENGTH OF ELECTROMAGNETS

Planning Experimental Procedures

There are three main factors which affect the strength of an electromagnet:

  1. The size of the current.
  2. The number of turns the coil has.
  3. What the core is made of.

For this investigation, I intend to explore how the number of coils of insulated wire around an iron core effects the amount of paper clips attracted to the electromagnet.

My prediction using results from the pilot study is that if I increase the number of coils the strength of the electromagnet will also increase (more paper clips will be attracted to the EM). However I have read that in theory, the strength of the EM will double as the number of coils are doubled (EM strength is directly proportional to the number of turns of coil).  

I will use the following apparatus for this experiment: paper clips, soft iron core, insulated wire, voltmeter, ruler, wire stripper, crocodile clips and power pack. I have chosen this equipment because it suits the experiment I am doing and should also give me accurate results. The power pack will allow me to work with a safe voltage and to convert mains AC to DC.

First I will connect the voltmeter to the power pack. From the voltmeter I will attach two connecting wires to the crocodile clips. I will then cut a large length of insulated wire and wrap the desired number of coils tightly around the soft iron bar, this is my electromagnet (EM). Then I will remove 3cm of the plastic coating around the copper wire using a wire stripper. I will then connect the ends of the exposed wire to the crocodile clips. Then the power pack will be turned on and set at the correct voltage of 2V. Then I will hold the EM two centimetres above the container holding the paper clips. I will then remove the paperclips onto a blank sheet of paper and switch of the power supply. I will then count the number of paper clips picked up with the EM and record the results in table 1. I will then increase the number of coils and repeat the above procedure. The following diagram represents the apparatus set-up:

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In the pilot study I found that the length of the copper wire at the start had to be 2m long. I also took some readings which gave a correct pattern of results, therefore I decided to use the same method of doing the actual experiment.

The magnetic field around a wire is circular and this field weakens as you move away from the wire as shown below. (Diagram 2)

The field is ...

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