Copper - electromagnets. Making them stronger.

page 4

Making them stronger

Picture 8. We can make the electromagnet stronger by increasing the current, the number of turns or by putting in a soft iron core.

We can make electromagnets stronger in a number of ways. Here are some of them:

Let's look at each of these.

	Bigger current

		A bigger current will make a stronger magnet. However, there is a limit to how much current can flow in the wires before it gets too hot. Also, a bigger current means that more energy is wasted (as heat) in the coil and in the connecting wires. So it is often best to try to increase the strength by adding more turns rather than increasing the current.

	More turns

		Imagine you have an electromagnet made from a single turn of wire. You then add another turn. It's like putting another electromagnet next to the first one. So the strength of the magnet increases. The more turns, the stronger the magnet will become.

Picture 9. The magnetic particles in a soft iron nail will line up with the magnetic field when the current is switched on.

	Iron core

		Iron is a magnetic material. There are magnetic particles inside the iron. In soft iron, these particles will line up with an external magnetic field. In this way, the soft iron core behaves like a magnet itself. Once the external field is taken away, the core will return to normal. Imagine we put a piece of soft iron in the middle of a coil of copper wire. When we switch on the current, the coil becomes an electromagnet. But also, the soft iron core becomes a magnet. It will add to the strength of the electromagnet. The effect of the soft iron core is much more than doubling the current or the number of turns.