electromagnetism - cpb-us-e1.wpmucdn.com · what is electromagnetism? (1820) hans christian oersted...
TRANSCRIPT
Electromagnetism
Section 1: What is Electromagnetism?
What is electromagnetism?
(1820) Hans Christian Oersted produced a current in a wire during a lecture.
When he brought a compass near the wire, the compass changed direction.
Whenever he turned on the current in the wire, the compass needles lined up around the write in the shape of a circle.
Electric Current & Magnetism
Wherever there is electricity, there is magnetism
An electric current produces a magnetic field
This relationship is called electromagnetism
Electric Current & Magnetism
How can you observe electromagnetism?
Compass & electric current
A compass needle normally points north because it aligns itself with Earth’s magnetic field
The needles of compasses surrounding a current will align with the current, producing a circle
The Magnetic Field
The magnetic field produced by a current has three distinct characteristics:
1. The field can be turned on and off
2. The field can have its direction reversed
3. The field can have its strength changed
The Magnetic Field
You can turn a magnetic field produced by a current on and off…
How can you turn the magnetic field off?
Simply by turning the current off!
The Magnetic Field
You can change the direction of a magnetic field…
How can you change the direction?
Simply by reversing the direction of the current!
Solenoids
You can change the strength of a magnetic field produced by a current…
How can you change the strength? Simply by looping, or winding, the
wire of the wire!
The strength will increase as the number of loops or coils increases
A solenoid is a coil of wire with a current.
Electromagnets
A solenoid with a ferromagnetic core is called an electromagnet.
The magnetic field of an electromagnet can be hundreds or thousands of times stronger than the magnetic field of the current alone
Basically, an electromagnet is a strong magnet that can be turned on or off.
Electromagnets
You can increase the strength of an electromagnetic field…
1. Increase the current in the solenoid
2. Add more loops of wire to the solenoid
3. Wind the coils of the solenoid closer together
4. Increase the strength of an electromagnet by using a stronger ferromagnetic material for the core
Common Electromagnets
Audiotapes
Videotapes
Computer hard drives
Credit cards
Doorbells
Radios
Refrigerators
Video Questions http://videos.howstuffworks.com/search.php?media=video&terms=electromagnet
1. Did the electromagnetic watch have an affect on the bullet?
2. What happened when the Mythbusters Crew increased the magnets?
3. How many degrees did the turkey increase?
4. What caused this increase?