Foreword Magnetic materials are found all around us in everyday life, from the magnets sticking to a refrigerator door to the tape in a cassette recorder.
Magnetic forces make motors turn and telephones speak.
They deflect particles in atomic accelerators and detect bad checks and credit cards. This teaching module is designed to provide a better understanding of the nature of magnetic materials and their use in magnetic recording devices such as audio cassette recorders, VCR's and floppy disks in personal computers. It will demonstrate the direct connection between the basic physics of magnetism and the modern technology of the multi-billion dollar recording industry. In this module, the direct observation of these domains under a microscope provides a beautiful example of ''visible physics'' and of a research tool that has led to great improvements in materials and devices within recent decades. This is one of a series of hands-on experiments that illustrate several fundamental ideas of magnetism and magnetic materials.