The Magnetism Unit: I Hope You Will Be Attracted To It

Transcription

1 The Magnetism Unit: I Hope You Will Be Attracted To It

2 Magnetism - The force that a magnet has upon magnetic materials. Name some items that use magnet in order to operate properly.

3 The Earth is a very large magnet. Like any magnet, it has a north pole and a south pole. s n

4 Molten metals churning in the Earth s core create a magnetic field around the entire planet. S N The lines of force come out of the Magnetic South Pole, extend into outer space, and plunge back in at the Magnetic North Pole.

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7 A compass needle is magnetic and floats freely to align with Earth s magnetic field. The needle always points north

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10 Movement of the magnetic north pole from 1600 to Canada

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12 Magnetic Declination is the term given to the difference between Geographic North and Magnetic North. Geographic North Pole Magnetic North Pole Angle of Declination

13 The location of the magnetic north pole is known to wander about the earth's geographic north pole. It is currently in the islands of northern Canada. Geographic north pole

14 Angle of declination due to two north poles MAGNETIC NORTH POLE GEOGRAPHIC NORTH POLE GEOGRAPHIC SOUTH POLE MAGNETIC SOUTH POLE

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16 Global Positioning Satellites - GPS The need for compasses is not as great as it once was, thanks to GPS technology

17 Global Positioning Systems

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19 Aurora Borealis (Northern Lights) Solar particles entering the Earth s atmosphere at the Magnetic North Pole excite our atmospheric gases to create glowing plasma.

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26 Auroral view from space includes north geographic and magnetic poles

27 Magnetism Found!! Over 2000 years ago the Greeks found an unusual rock that attracted objects containing iron. This mineral had magnetite in it.

28 Years later, magnetite was used as a compass because it always lined itself up with Earth s magnetic field.

29 Magnetic materials are made up of groups of atoms called domains. The domains must line up in order for that metal to become a magnet. Magnetized domains Not magnetized

30 Each domain is like a tiny magnet made up of millions of atoms. Domains must be lined up in order for a material to become a magnet. Not magnetized Magnetized domains

31 Three naturally occurring magnetic metals : Iron Nickel Each of these materials easily allow their domains to be lined up. These are ferromagnetic metals. Cobalt

32 Rules in Magnetism Rule 1) Magnets have a magnetic field.

33 All magnets have an area of force around them called a magnetic field. The lines of force in a magnetic field come out of the north pole and go into the south pole.

34 Rule 2 Opposite Poles Attract N S N S

35 N N Rule 3) While Like Poles Repel

36 Three main types of Magnets: Temporary loses magnetism after short time. Permanent keeps magnetism for longer periods. Electromagnet Magnetism can be turned on and off with electrical current.

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38 Electromagnet A magnetic field that is created by running an electrical current through a wire that is wrapped around an iron core. Makes an electromagnet stronger: 1. More coils or wraps of wire 2. More current of electricity

39 Electromagnets are used in nearly all parts of our daily lives.

40 Maglev Trains Floating on a bed of magnetism.

41 Magnetic fields attract and repel the train down the track. The magnets keep the train perfectly centered and off the track.

42 Two different track styles. This style allows the train to run within two electromagnet rails.

43 While this style uses a magnetic field wrapped around the track.

44 Magnetic Resonance Imaging

45 MRI - Magnetic Resonance Imaging

46 MRI image

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49 MRI vs. CT Scan Both offer high detail, layered imaging Both machines appear similar to the untrained CT uses computer aided x-ray technology MRI uses strong magnets MRI used in softer tissues and pregnant women CT scan gives faster results

50 CT (Computer Aided Tomography) machine

51 CT image

52 MRI : Caution must be taken

53 Generators convert mechanical energy into electrical energy.

54 Generators generate electricity by spinning copper coils inside of a magnetic field.

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56 Alternative energy sources use many means to spin copper coils inside of magnetic fields. The electrons in the copper bounce from atom to atom when placed in a magnetic field. This is current electricity.

57 Electromotor - An electromotor converts electrical energy into mechanical energy by spinning an electromagnet inside of a magnetic field. Mechanical energy is the ability to do work.

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60 Electromagnet Generator Electromotor Converts one form of energy to another Converts energy Converts energy Uses copper coils Uses copper coils Uses copper coils Increase coils, increase performance Increase coils, increase perf Increase coils, increase perf Uses electricity Makes electricity Uses electricity Creates an electromagnet Does not create electromag Creates an electromagnet No permanent magnet Uses permanent magnet Uses permanent magnet

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