Magnetism Introduction Video https www youtube comwatch v58

Magnetism Introduction Video • https: //www. youtube. com/watch? v=58 Gxe 2 ew. HGo

Magnetism

Magnet: Is an object made from magnetic materials with the ability to attract pieces of other magnetic materials and attract or repel other magnets.

Magnetic Material: Fe 3 O 4 (loadstone) is the only naturally occurring magnet. Iron, Steel, Nickel and Chromium are the only known materials that can be made into magnets.

Magnetic Field: The region around a magnet where the magnetic forces act.

Magnetic Poles: The magnetic properties of magnets appear to be concentrated at the two ends. The ends of magnets are called magnetic poles or simply “poles”. There is a North and a South pole.

Poles and Charges: Magnetic poles are not the same thing as electrical charges. It is WRONG to use the term ‘poles’ for charges or ‘charges’ for poles.

Interaction between poles of magnets: Similar poles repel while opposite poles attract. Both poles ATTRACT non-magnetized pieces of magnetic material. Magnets have no affect on non-magnetic materials.

The earth is like a giant magnet! The nickel iron core of the earth gives the earth a magnetic field much like a bar magnet.

For Every North, There is a South Every magnet has at least one north pole and one south pole. If you take a bar magnet and break it into two pieces, each piece will again have a North pole and a South pole. S N S N

No Monopoles Allowed S N

Permanent Magnets: Keep magnetic properties for a long time Temporary Magnets: Only keep magnetic property temporarily

Making Permanent Magnets: Mechanical method. Any piece of magnetic material can be made into a magnet by stroking it with an existing magnet in a particular way. Steel makes the best permanent magnets.

Making Permanent Magnets: Electrical method. Passing direct current through an insulated wire wrapped around a piece of magnetic material (except iron) will make the material a magnet. The strength of such a magnet depends on the number of turns of the wire and the strength of the current but not on the duration for which the current is passed.

Electromagnets (temporary magnet): Electromagnets are made by exactly the same method as that for permanent magnets. The only difference is only Iron can be used. Summarize: When the current is flowing in the wire, the iron is a magnet but when the current is switched off, the iron quickly demagnetizes.

Temporary Magnet

The Concept of “Fields” Michael Faraday realized that. . . A magnet has a ‘magnetic field’ distributed throughout the surrounding space

Electromagnetic Induction (Faradays Law): Electromagnetic induction is the process by a permanent magnet that can be used to produce electrical current by moving a loop of wire through a magnetic field. Phet. colorodo. edu -> Physics -> Electricity ->

Loudspeakers work by this idea •