Unit 3 Electricity Magnetism Magnetic Field Currents Plasmas

Unit 3 Electricity & Magnetism Magnetic Field, Currents & Plasmas Physics 5 h Students know changing magnetic fields produce electric fields, thereby inducing currents in nearby conductors Physics 5 i Students know plasmas, the fourth state of matter, contains ions or free electrons or both and conduct electricity

Magnets l All magnets have a MAGNETIC field around them, at ALL times

Magnets l Static: If a magnet is NOT moving it only has a magnetic field l Moving: If a magnet is moving it has BOTH a magnetic field AND an electric field

Magnetism l It is the force of attraction or repulsion of a magnetic material due to the arrangement of its atoms, particularly its electrons. l All magnetic phenomena result from forces between electric charges in motion.

Magnetic Field The region where the magnetic forces act is called the “magnetic field”

Magnetism Video l http: //glencoe. mcgraw- hill. com/sites/dl/free/0078778069/161383/ 00050755. html

Magnetic Domains l Magnetic substances like iron, cobalt, and nickel are composed of small areas where the groups of atoms are aligned like the poles of a magnet. These regions are called domains. All of the domains of a magnetic substance tend to align themselves in the same direction when placed in a magnetic field. These domains are typically composed of billions of atoms.

Earth is a magnet l Earth exerts magnetic forces and is surrounded by a magnetic field that is strongest near the North & South magnetic poles.

We use the Earth’s magnetic field to find direction l The needle of a compass always points toward the magnetic south pole l We call this direction “NORTH” (remember, opposites attract)

Electricity & Magnetism-how are they related? l When an electric current passes through a wire a magnetic field is formed.

What is an electromagnet? l When an electric current is passed through a coil of wire wrapped around a metal core, a very strong magnetic field is produced. This is called an electromagnet

How can you produce electric current from magnets? l By moving a magnet through a wire that is coiled or in the form of a loop.

What are electric motors? l An electric motor is a device that changes electrical energy into mechanical energy.

Current Electricity It is different than static electricity in that static electricity is stationary or collects charges on the surface of an object, whereas current electricity has electrons flowing very rapidly through a conductor. l Current electricity has electrical pressure or voltage. l Electric charges flow from an area of high voltage to an area of low voltage. l

There are some similarities between the flow of water in a pipe and the flow of electric current through a circuit

Plasmas l Plasmas are made up of free electrons and ions of the element ---> charged particles l Therefore, they are electrically conductive. l Plasmas do not have a definite shape.