1. EET 110 - Survey of Electronics Chapter 15 - Magnetism

2. Magnetism –the property of a material to attract pieces of iron or steel. Magnetic materials –iron, steel, nickel, cobalt Magnetized with North and South ‘polarity’ –Temporary and Permanent magnets

3. Law of Magnetic Poles –like poles repel –unlike poles attract –Magnetic force varies inversly as the square of the distance. Magnetic FLUX –lines of magnetic flux extend across a space which is in a strong magnetic field.

4. The MAGNETIC FIELD is made up of these lines of magnetic force or flux. Characteristics of lines of magnetic force –line of force never cross one another –lines of force form closed loops –… travel from the north pole to the south pole outside the magnet and south to north inside it. –… follow the easiest path, passing most easily through soft iron

5. –The stronger the magnet, the greater the flux density (lines per square inch) –Lines of force repel each other –There is no known insulator for lines of force. Magetic shielding –soft iron shields the lines of magnetic flux.

6. Electrons and magnetism magnetism and electricity affect one another. –Theory that spinning electrons generate a magnetic field Uses of magnetism –PM Motors –Speakers –Generators

7. Chapter 16 - Electromagnetism A conductor carrying a current generates an magnetic field. –‘left hand rule’ The greater the current, the greater the magnetic field magnetic field about a coil –each conductor adds to the magnetic field generated by the others.

8. A magnet can generate an electric current or vice-versa Uses of Electro-magnets –transformers –electric buzzers/bells