Now at last we introduce electromagnetism - the main subject of this whole section.
Youtube video, suitable whether of not you have the board with you.
See board images.
Tutorial guide for when you have the board with you.
Again, we have two boards for you to look at here. The first is a magnetic version of something called Newton’s Cradle and its rather fun to watch. Each of the suspended parts contain magnets that are repelling their neighbours, so they bump each other away when you start an end one swinging. the energy being transferred along the line.
The second board is made of two layers of Perspex with a sealed gap between them. In the gap are some very small bits of steel (iron filings). Pick up the board and shake it so some of these are in the middle of the board. Now place it over the board with the magnets on it. You will see the iron filings stand up where they are over the magnets, it's as if you can see their magnetic field. Now move the top board up and down and you will see the filings always stand up over the magnets.
Shake the board again to get the iron filings smooth, then press the left side of the rocker switch and watch the iron filings. You will see a pattern occur over an item that is under the board. This is coil of wire round a special rod called a ferrite core. The patterns in the filings are very similar to the ones made by the magnets. This is because passing an electrical current through a coil of wire actually turns it into a magnet. It's called an electromagnet.
This is a really amazing thing and something that is very important to how many electrical gadgets work and we will see this later. The left side of the rocker switch uses 3 of the batteries, by pressing the right side you will increase the current going through the coil because you will use all 6 batteries and you will see more of the iron filings standing up because the magnetic field is stronger.
Some follow-up ideas to try...