Electromagnetism

Magnetism from Electricity 1. Electric current can produce a magnetic field and the direction of that field depends on the direction of the current.

Solenoids 2. Magnetic fields can be increased by increasing the amount of current. A solenoid is a coil of wire that produces a magnetic field when carrying an electric current.

How to increase magnetic field in a solenoid a. more loops = larger magnetic field b. more current = larger magnetic field

Electromagnetic Electromagnets consists of a solenoid wrapped around an iron core. a. The field produced by the solenoid causes the domains inside the iron core to become aligned making it stronger than a regular solenoid. b. Electromagnets can be turned off and on.

c. You can additionally make the electromagnetic stronger by increasing loops, the size of the core or the current in the wire. d. Strong electromagnets can lift trains!

Magnetic Force & Electric Current Not only can an electric current cause magnets to move but Magnets can cause electric current to move!

Transformers A transformer increases or decreases the voltage of alternating current. Often located on top of electrical poles to decrease voltage before it goes in to your home.

Applications of Electromagnetism Doorbells – doorbells contain a solenoid with an iron rod inserted part way. The current is controlled by the button. Press the button and a switch in the solenoid circuit closes. The magnetic field that is created pushes the rod into the bell.

Electric Motors An electric motor is a device that changes electrical energy into kinetic energy. The motor uses magnets to create motion. The electrical current enters into the motor to the commutator which turns the armature a half turn, current is reversed which turns the armature another half turn until it spins.

Electricity from Magnets Electromagnetic induction is when electric current is produced by changing a magnetic field.

Applications Generators use electromagnetic induction to convert kinetic energy to electrical energy. A coil of wire is placed between the poles of a permanent magnetic. As the crank is turned the coil cuts through the magnetic field lines and induces an electric current in the wire.