1. T.O.C: Current Can Produce Magnetism
Ch. 3; Lesson 3.2
T.O.C:
Current Can Produce Magnetism

2. Electric Current Produces a Magnetic Field
1800’s- Hans Christian Oersted discovers a connection between electric current & magnetism :
Electric current produces a magnetic field which can cause objects to become magnetized
Electromagnetism w.w- magnetism that results from an electric current.
When a charged particle –electron- moves; it produces a magnetic field.
If wire is straight- magnetic field is like a tube around wire, if wire is loop- magnetic field is stronger & is concentrated inside the loop. The more coil, the more concentration → stronger magnetic field
Coiled wire w/ charge flowing has magnetic field like a bar magnet.
Create coil/wire/bar magnet illustration

3. Making an Electromagnet
Electomagnet -w.w. – magnet made by placing a piece of iron or steel inside a coil of wire.
As long as the coil carries a current, the metal will act like a magnet & increase the magnetic field of the coil.
When current is turned off, magnetic domain in the metal becomes random again & magnetic field/properties are gone.
The more coils of wire around metal → stronger electromagnet
Some of the most powerful magnets in the world are hug electromagnets used in scientific experiments.

5. Uses of Electromagnets
B/c they can be turned on/off, they have more uses than permanent magnets.
Ex:
Crane in junkyard w/ huge magnet or like the one in the background image move extremely large objects..
Computers use electromagnets to store info
ATM/Debit/Credit cards have information in strip swiped at store/bank – don’t store cards w/ strips facing each other b/c the magnetic field can cause info to erase
LAB-Build an Electromagnet
Labs/Activities section of Notebook- Leave space between each ↓
List materials needed, -wire, iron nail, battery, paper clip
How you built your magnet. –build without a switch 1st
Make a switch for you electromagnet.
Change the amount of coils in your wire- what was your electromagnet with less coils like? With more coils?
Change battery sizes- does the size of the battery affect the power of your electromagnet positively, negatively, or not at all?

6. Motors use Electromagnets
Electric motors convert the energy of an electric current into motion by using current & magnetism
100’s of devices contain electric motors: blender, mixer, fans, power tools.
Almost anything with moving parts that uses current has an electric motor.
About Motors
Although they may look different in size/appearance, all motors have similar parts & work in similar ways.
Main parts of an electric motor:
Voltage source, a shaft, and electromagnet, & at least 1 additional magnet. The shaft of the motor turns the other parts of the device.
When current from the voltage source flows through the coil, a magnetic field is produced around the electromagnet. The poles of the magnet interact with the poles of the electro magnet, causing the motor to turn.
The poles of magnet/electromagnet constantly exert force pushing/pulling each other causing the motor to turn.
When the poles line up with their opposites, part of the motor – commutator - reverses the polarity of the electromagnet & the motor keeps turning.
The more coils on the electromagnet in the motor, the stronger the motor

8. Uses of Motors
Motors can move very small objects- like battery operated hands on a wrist watch; or very big, such as the motors that power subway trains.
Motors can move objects in any direction. Ex: some motors move objects in circles- CD player, gaming device- & some move objects up/down- power window motors in cars move the windows up/down
You can have more than 1 motor in the same device.
LAB- Build an Electric Motor

9. 3.2 Review Q’s (12 pts
Explain how electric current & magnetism are related. (2 pts
Describe 3 uses of electromagnets. (3 pts
Explain how electric energy is converted into motion in a motor. (3 pts
How does an electromagnet differ from a permanent magnet? (2 pts
What 2 ways can you increase the strength of an electromagnet? (2 pts)