Chapter 18 Magnetism Student Notes

Transcription

1 Chapter 18 Magnetism Student Notes Section 18.1 Magnets and Magnet Fields Magnets More than discovered deposits of a that was a. The mineral is now called. These magnets were used by the ancient peoples as to guide. Today, the word magnetism refers to the and. any material that and materials that contain iron the attraction or repulsion of magnetic materials o Magnets or other magnets. o Common metals affected by magnetism are,, and, such as, glass and, have that flow in. Magnetic Poles Magnetic poles are where the exerted by the magnet is strongest. the on any magnet, no matter what its All magnets have a and a. the attraction or repulsion between magnetic poles Magnetic poles that are alike repel each other. Magnetic poles that are unlike attract each other. Poles- of a magnet Every magnet has two poles (N) pole (S) pole Even if you break a, each half will have a and a No Monopoles Allowed It is not possible to end up with a single North pole or a single South pole, which is a ("mono" means one or single, thus one pole). Even of magnetic materials act as tiny magnets

2 Making a Magnet Materials that are will also stay magnetized for a A magnet that is hard to magnetize but tends to keep its magnetism is called a. Ex: A material that is tends to its magnetism quickly A magnet made of this kind of material is called a Ex: Shaped Magnets The two ends of a are the north and south poles. A magnet shaped like a disk has opposite poles on the and of the disk. Magnetic always connect the north pole and the south pole of a magnet. Magnetic Fields realized that... A magnet has a distributed throughout the surrounding space A magnet is by a. A magnetic field on other magnets and objects made of magnetic materials. The to the magnet and far away. A magnetic field also has a & illustrated by. the lines that map out the magnetic field around a magnet Magnetic field lines spread out from one pole, around the magnet, and return to the other pole forming a. a grouping of billions of atoms that have their magnetic fields lined up in the spin around when placed near a magnetic field. An unmagnetized substance looks like this While a magnetized substance looks like this

3 Earth as a Magnet has a magnetic field with. This magnetic field enables us to use Our planet's rotation causes molten in its outer core to o Creating and a. a British scientist Showed that the Earth has north and south poles like a The Earth is surrounded by a magnetic field which extends far into space. Called the. of the Earth are different from the of the Earth. the Magnetic Pole is located near the geographic the Magnetic Pole is located near the geographic Earth s Magnetic Poles Earth s magnetic poles with. Sometimes places so that Earth s south magnetic pole is the southern hemisphere near the geographic south pole. Compasses Compasses are used to Compass are and respond to the of the We use the Earth s magnetic field to find direction. of birds The needle of a compass always points toward the magnetic. The compass needle points toward the geographic Magnetic Effects The most visible effect of the earths magnetic field is a, called an between the and other particles in the upper atmosphere create glowing lights

4 18.2 Magnetism from Electric Currents Electromagnetism In 1820, Han, a Danish physics teacher, found that and are related. Oersted hypothesized: Electric current must produce a around the, and the direction of the with the direction of the current. When a compass was brought near electric current, the compass needle When an passes through a wire a. The magnetic field depends on the in the wire. The direction of the magnetic field around the wire when the direction of the. As the in the wire the of the magnetic field. Electromagnetism relationship between electricity and magnetism Oersted s discovery is of new tools based on the principles of. When an electric current is of wire wrapped around a metal core, a very strong magnetic field is produced. This is called an. The on the, the amount of, and the of the. Solenoid A single wire wrapped into a cylindrical wire coil is called a. A type of The solenoid s magnetic field the. The magnetic field a solenoid is than the field in a. The field inside the solenoid with the iron core can be more than times greater than the field inside the. Properties of Electromagnets Electromagnets are because the magnetic field is in the solenoid. The of the magnetic field : o by adding more to the solenoid o by increasing the through the wire. Electromagnet has a and a.

5 If placed in a magnetic field, an along the, just as a compass needle will. An electromagnet also will materials and be or by other magnets. Electromagnetic Devices A galvanometer gives a. An electromagnet that interacts with a. The the passing through the wires, the the galvanometer interacts with the permanent magnet. Galvanometers are used as in cars and many other applications. Functions as an to measure current, when other circuit elements are used. Functions as a to measure voltage. Electric Motors device that changes energy into energy An electric motor is made up of an and a A fan uses an electric motor Almost every in which something moves contains an. A simple electric motor also includes components called and a. The brushes to coil using the. The commutator is used to the. Form a between the and the Electric Currents from Magnetism Electromagnetic Induction The process of by moving a through a wire coil. Causes to move the wire. Working independently in 1831, Michael in Britain and Joseph in the United States both found that: Moving a of wire through a magnetic field caused an to flow in the wire. They also found that moving a magnet through a loop of wire.

6 Generators a device that converts energy into energy A generator uses in a magnetic field to produce an How a Generator Works a current can be induced in a loop of wire by the loop inside a due to the changing direction of the wire, an is produced Using Electric Generators The type of generator in a car, is called an a. The alternator provides to operate lights and other accessories. Electrical energy comes from a with generators. Produces the that you. The coils in these generators of wire wrapped around. The rotating magnets are connected to a (TUR bine) a large wheel that rotates when,, or. is then converted to energy as the steam pushes the turbine. : Electricity and magnetism are two aspects of a single force. energy results is an example of electromagnetic energy. are made of both electric and magnetic fields. Transformers A transformer is a or decreases voltage. a transformer consists of of wire around a the first coil, called the, is connected to the the second coil, called the, is connected to the a load is something that uses electricity, such as a light bulb or a motor Two types of transformers: : a transformer that voltage :a transformer that voltage