1. What is an alternating current (AC)? What is an AC generator? What is an AC transformer? How to calculate a transformer’s expected step-up or step-down AC voltage? ES Lesson 7: AC electricity © 2012 C. Rightmyer, Licensed under The MIT OSI License, 20 July 2012

2. The magnetic field generated by a coil of wire that has a current flowing through it. Electricity and Magnetism, Gareth Stevens Publishing, Steve Parker, 2007

3. A compressed coil of wire with a current passing through it acts just like a button magnet. [Intro to College Physics, Appleton-Century-Crofts, R.D. Rusk, 1960]

4. ES demo 7-1. A moving magnetic field inside a coil of wire induces current in that coil. Make: Electronics, O’reilly [Publishing], Charles Platt, 2009 BE demo 1-2

5. How does an AC generator work?

6. Continuous slip rings required to connect current to the load. [Intro to College Physics, Appleton-Century-Crofts, R.D. Rusk, 1960]

7. Direction and amplitude of generated voltage 7 IQT Corporation, Electric Pizza, An in house course, 2010

8. Electrical power delivery system Electricity and Magnetism, Gareth Stevens Publishing, Steve Parker, 2007

9. Direction and amplitude of the generated current [Intro to College Physics, Appleton-Century-Crofts, R.D. Rusk, 1960]

10. How’d those electrons get into your outlet?

11. ES demo 7-2. Use a toy generator to produce AC and DC voltages. Display output using a multimeter and oscilloscope. BE demo 7-1

12. ES demo 7-3. Transformer operation using two AC voltmeters and an oscilloscope. ~ 1000 turns ~ 142 turns AC VOM 120 Volts AC AC VOM ~ 17 Volts AC Oscilloscope AC Sine Wave 1 Megohm resistor BE demo 1-4

13. Output on the secondary coil Output on the secondary coil depends on input voltage and turns ratio (V s ) = V p (N s / N p ) where: V s = voltage in secondary V p = voltage in primary N s = number turns in secondary N p = number turns in primary

14. Back up charts

15. Fields associated with different shaped magnets [Intro to College Physics, Appleton-Century-Crofts, R.D. Rusk, 1960] [A.O.Smith: The AC's and DC's of Electric Motors]

16. Mutual coupling between electromagnetic fields [Intro to College Physics, Appleton-Century-Crofts, R.D. Rusk, 1960] (a) strong coupling (b) no coupling (c) weak coupling

17. One way to measure input and output currents LED VOM Amps VOM Amps AC Generator (Volts)

18. Constructing a transformer with a circular magnet

19. Second method for measuring the currents Light VOM V ac VOM V ac AC Generator (Volts)