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2.8.2
Electricity + Magnetism
Electric Current + Magnetism- are related
Moving charged + magnetic fields
An electrical current creates a magnetic field
Grater the current – grater the magnetic field
Electromagnets- a temporary magnet made by wrapping a wire coil carrying an electric
current around and iron core
Figure 9 B Solenoid- single wire wrapped into a cylindrical wire coil
Solenoid wrapped around iron core makes electromagnet
Properties of electromagnets- temporary because magnetism us only present when current
flows
More turns in wire = stronger strength
One end is south pole + one end is north pole
Magnetic properties can be controlled by changing current
Stereo speakers, electric motors
(Read section pg. 233) Using electromagnets to make sound
Electromagnet is connected to speaker core
Electromagnet changes electric energy to mechanical energy,
which vibrates the speaker core to produce sound
CD produces varying voltage according to music
Varying voltage produces varying current connected to core
Varying current causes electromagnet to change, which is surrounded by
permanent magnet
Permanent magnet vibrates because charging magnetic field which is
connected to the core
(Read pg. 234) Making an electromagnet rotate
A solenoid wrapped around a iron cylinder with an electric current moving
through rotates when between a north and south pole
Rotates until the solenoid with the current going through is stable and
attracted to the opposite poles
Changing the current to make the solenoid rotate
Galucnometers- devices that use and electromagnet to measure electric current
Gauges is your car
(Figure 12) Using Glaucnometers
Used in cars in gasoline gauge
The current changes in the solenoid depending on the sensor in the gas tank
Preset for full or empty
Electric motors- a device that changes electrical energy into mechanical energy
(Figure 13) What ate some things in your house that use and electrical motor?
Simple electric motor main parts are wire coil, permanent magnet, and
source of electric current
Forms closed electric circuit with commentator and brushes
Making the motor spin- the electric current is sent through wire which creates
electromagnet. The electromagnet spins and then the brushes disconnect from
commentator. The inertia of the coil keeps is spinning. Commentator reverse flow of
electric current, which cause coil to be repelling. The rotation continues until the magnets
are at opposite poles. The current reverses and process is started again.