ELECTROMAGNETS

REVIEW

• All matter has protons & electrons

• Electric current is the flow of charge through a material

• Amount of charge that passes through wire in a unit of time is rate of current flow

RELATING ELECTRICITY TO MAGNETS

• Electric current creates magnetic field

• Any electrical charge in motion creates magnetic field

• Direction of current determines direction of magnetic field

• Reverse current, magnetic field reverses

• Can control a magnetic field by using an electric current

SOLENOIDS

• Current carrying coil of wire with many loops

• Creates magnetic field that can be turned on & off by switching the current on & off

USES OF ELECTROMAGNETS

• Lifting heavy pieces of scrap metal

• Recording information on audiotapes, videotapes, computer disks, or credit cards• Talk into a microphone, the vibrations of your voice are change into an

electric current • Current is used in an electromagnet in the recoding head of the tape recorder

to produce magnetic field

WAYS TO INCREASE STRENGTH OF ELECTROMAGNET

• Increase current in the solenoid

• Add more loops of the wire

• Wind the coils closer together

• Using stronger ferromagnetic material as core

• https://www.youtube.com/watch?v=emlzh9XXWgQ

HOW TO GET ELECTRICITY TO YOUR HOUSE

• http://www.childrensuniversity.manchester.ac.uk/interactives/science/energy/electricity/

ASSESSMENT!

• The region in which magnetic forces act is called a • Line of force• Pole• Magnetic field• Field of attraction

• An example of a ferromagnetic material is• Plastic• Wood• Copper• iron

• The person who first suggested that Earth behaves as a magnet was• Ampere• Oersted• Gilbert• Columbus

• The region in which Earth’s magnetic field is found is called the• Atmosphere• Stratosphere• Aurora• magnetosphere

• A coil of current-carrying wire with an iron core is called • Ferromagnet• Electromagnet• Compass• Maglev

TRUE OR FALSE

• If false, replace the underlined word to make it true

• Like poles of magnets repel each other

• The type of magnetic mineral found in nature is called platinum

• A compass needle points in the direction of Earth’s geographic north pole

• You can increase the strength of an electromagnet by adding more turns of a wire to it

• Explain why you are not left with one north pole and one south pole if you break a magnet in half.

• How does a material become magnetic?

• How does Earth act like a magnet?

• What is an aurora? How is it produced?

• Why does a compass needle change direction when it is placed near a current-carrying wire?

• The created magnetic field interferes with Earth’s magnetic field