1. Warm Up #18
How do direct and alternating current differ?

2. Lesson 3: Making an Electric Current with Magnets
Ch. 10 Magnetism
Lesson 3: Making an Electric Current with Magnets

3. Essential Questions
How can a wire and a magnet produce an electric current?
How do electric generators create an electric current?
How are transformers used to bring an electric current into your home?

4. Why does the Pendulum Slow Down? ACTIVITY
Using a thread, suspend a strong magnet from a ring stand about0.5 cm off the table
Pull the pendulum back 5 cm and gently release
Count the swings until the pendulum stops
Take a 3cm wide strip of foil and place on table so magnet doesn’t touch it
Repeat step 2 and 3.

5. Generating Electric Current
A magnet is moved through a wire coil that’s part of a closed electric circuit
As magnetic field moves over the wire coil, an electric current is produced in the circuit
When magnet stops moving there’s no current
Direction of the current depends on the direction in which the magnet moves.

6. Simple Electric Generator
Electric generator – a device that uses a magnetic field to transform mechanical energy to electric energy
A crank rotates a wire coil through the magnetic field of a small permanent magnet, which produces an electric current in the circuit
Current continues as the crank continues to rotate the coil within the magnetic field

7. Direct Current and Alternating Current
Direct current – an electric current that flows in 1 direction
Alternating current – an electric current that changes direction in a regular pattern

8. Generators and Power Plants
Turbine – a shaft with a set of blades that spins when a stream of pressurized fluid strikes the blades
Connected to a generator to supply mechanical energy

9. Transformers – Changing Voltage
Transformer – a device that changes the voltage of an alternating current
Has 2 wire coils wrapped around a single iron core
Alternating current in primary coil produces a continually reversing magnetic field, which produces alternating
current in the
secondary coil

10. Electric Energy – From Power Plant to Your Home
BrainPop – Electromagnetic Induction