1. Magnetism Generators and transformers Catherine Mortimer-Hawkins, IEST

2. Generators As the coil is rotating, EMF- voltage is produced that makes a current flow. The generator gives out AC (alternatingcurrent). AC generators = alternators.

3. Increasing EMF Increase the number of turns on the coil. Increase the area of the coil. Use a stronger magnet. Rotating the coil faster.

4. Twoholes in the wall! Maximum forward current Maximum reversecurrent 1 rotation The maincurrent in a house is AC. The current and voltage is varying all the time. Europesmainvoltage is 230 V and is an average.

5. Transformers AC voltagescan be increased or decreased by transformers!

6. Transformers AC-input voltage (primaryvoltage) willthrough the first coil set up a magneticfield in the ironcore. The magneticfieldwillalso be in the secondarycoil. The changingfieldwillinduce an AC in the second coil.

7. Transformers If the secondarycoil has moreturnsthan the primary the voltageincreases! If the secondarycoil has fewerturnsthan the primary the voltagedecreases!

8. If you want to read more… Generators: pages 226-227 Transformers: pages 228-229 (don’tbotherabout the calculations…)