1. 22.2 Alternating Current, Generators and Motors pp. 803 - 813 Mr. Richter

2. Agenda  Warm-Up  Review HW  Notes:  Generators  Alternating Current  Motors

3. Objectives: We Will Be Able To…  Describe how generators produce alternating current.  Describe rms current and voltage in AC circuits.  Compare and contrast electric generators to electric motors.

4. Warm-Up:  Imagine you have a disk with magnets around the outside that alternate north and south poles ( like the one at the front of the classroom). How could you use a magnet to make the disk spin?  Discuss at your table, and we will discuss as a class in a few minutes.

5. Generators and Alternating Current

6.  A generator is a device that uses induction to convert mechanical energy into electrical energy.

7. Generators and Alternating Current  The rotation of the turbine (fan) rotates a wire loop in a magnetic field, inducing current.  Because the orientation of the loop keeps changing, the current alternates.

8. Generators and Alternating Current  The alternating current produces an alternating voltage as well.  For simplicity, we discuss the rms voltage and current.  rms = “root mean squared”  RMS is the average distance from zero.

9. Generators and Alternating Current  For example:  The peak voltage (highest value) from a standard electrical outlet is about 170 V.  However, we usually only consider the rmf value of 120 V.

10. Motors

11.  An electric motor is a device that that uses magnetism to convert electrical energy into mechanical energy.  Usually the mechanical energy is in the form of a moving rotor, a rotating disk with alternating N-S magnets.

12. Motors  A wire uses alternating current to repeated switch the poles of an electromagnet.  The electromagnet alternately attracts and repels the magnets of the rotor.

13. Generators and Motors  Generators:  Motors:

14. Wrap-Up: Did we meet our objectives?  Describe how generators produce alternating current.  Describe rms current and voltage in AC circuits.  Compare and contrast electric generators to electric motors

15. Homework  p. 822 # 13, 14, 22  Write 2-3 complete sentences explaining the basic operation of an electric motor.