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SCIPAD - BIG IDEAS - BOOK 2
CIRCUITS AND MAGNETS
Method: 1. Tightly wind coils of wire around the test tube. Add as many loops as possible,
ensuring that they do not overlap.
2. Attach the ends of the newly formed coil to the alligator clips.
3. Turn the power supply to 12 V and adjust the variable resistor until the ammeter
reads the current your teacher has specified.
4. Bring your coil and test tube (electromagnet) near the paper clips and observe.
5. Turn off the power supply and place the iron nails inside the test tube.
6. Turn the power supply on and repeat step 4.
Observations: 
	

	
Further Investigations
You can also investigate decreasing the current flowing through the circuit and decreasing the
number of coils of wire around the electromagnet.
Conclusion: In order to increase the strength of an electromagnet you can 




Electromagnets
When an electric current flows in a wire it creates a magnetic field around the wire. By winding the
wire around an iron core, we can strengthen the magnetic field. Electromagnets are made from
coils like this. The magnetic field around an electromagnet is just the same as the one around a
bar magnet. It can, however, be reversed by changing the direction of the current (e.g. turning
the battery around). Unlike bar magnets, which are permanent magnets, the magnetism of
electromagnets can be turned off and on just by closing or opening a switch.
Investigating Electromagnets
Aim:		 To investigate factors that affect the strength of an electromagnet.
Equipment: Power supply, variable resistor (rheostat), test tube, length of wire (0.5 - 1 m),
ammeter, 3 x iron nails, paper clips, 4 x wires (2 with alligator clips at one end).
Initial set up: Assemble the circuit shown below.
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