22.2 Alternating Current, Generators and Motorspp. 803 - 813

Mr. Richter

Agenda

Warm-Up

Review HW

Notes: Generators Alternating Current Motors

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.

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.

Generators and Alternating Current

Generators and Alternating Current

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

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.

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.

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.

Motors

Motors

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.

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.

Generators and Motors

Generators: Motors:

Mechanical Energy

Spin Wire in Magnetic Field

Induce Current

Electrical Energy

Electrical Energy

Alternate Current in a Wire

Attract/Repel Magnets

Mechanical Energy

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

Homework

p. 822 # 13, 14, 22

Write 2-3 complete sentences explaining the basic operation of an electric motor.