Electricity and Magnetism

Moving Charges and Magnetic Fields

• Moving charges produce magnetic fields• Magnetic field lines form circles around a wire• The direction of the field reverses as the

current reverses

Electromagnets• A temporary magnet made by wrapping a wire

coil carrying a current around an iron core• Solenoid wire wrapped into a cylindrical coil

Speakers• Contains an electromagnet connected to a

flexible speaker cone made of paper, plastic, or metal

Electrical Energy Mechanical Energy Vibrates Speaker Cone Produces Sound

How A Speaker Is Made

• Speaker Video