Download 1 William Gilbert William Gilbert was born in

3d mag field
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William Gilbert
William Gilbert was born in England in 1544. He was a medical doctor but became most famous for his interesting
discovery about magnets. He studied many legends about magnets. In these legends, natural rock magnets were called lodestones. He studied how the earth acted like a huge, natural magnet and made lodestones work like a compass. Without a good compass, sailors sailing the seas would be lost forever! William Gilbert wrote a famous book called De Magnete, which is a latin word for "on the magnet". He died in 1603.
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The Ancient Greeks noticed that sometimes certain rocks would seems to want to touch
each other, and the same two rocks orientated slightly differently seemed not to want to touch
With your partner come up with an explanation for this phenomena
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Concept Check
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Hint
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More info about Faraday's accomplishments
will follow 6
Gilbert's Ideas about an invisible would revolutionize physics
The following are now the accepted magnetic field drawings. You need to know these Same for two souths, just arrows point the other way
­ Out from the North and into the South
­ Closer the lines are together the stronger the field
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Open Oersted Song
lyrics next slide !!!
Hans Christen Oersted
Magnetism Folder
Check out Attachements
Hans Christian Ørsted, one of the leading scientists of the nineteenth century, played a crucial role in understanding electromagnetism. In 1820 he discovered that a compass needle deflects from magnetic north when an electric current is switched on or off in a nearby wire. This showed that electricity and magnetism were related phenomena, a finding that laid the foundation for the theory of electromagnetism and for the research that later created such technologies as radio, television and fiber optics. The unit of magnetic field strength was named the Oersted in his honor.
What Oersted Noticed
Convential
http://www.phas.ucalgary.ca/physlets/oersted.htm
Ørsted proved that electric current sets up a magnetic field
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The Oersted Song
Walter Smith & Marian McKenzie 1999
(To the tune of “Get out ’ the way for Old Dan Tucker”)
FYI: Worsted is a type of wool fabric.
Disclaimer: We have no reason to think that Oersted was irritable, or that he wore red socks. D7
Hans Christian Oersted was a fine old Dane,
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He had magnets on the brain.
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He loved them all from pole to pole ­­
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Cut ’em in half but they still were whole ­
Refrain:
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So ­­­ get out ’ the way for old man Oersted
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He’s got socks of bright red worsted.
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Worsted’s sturdy, but it sure is itchy ­­
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That makes old Hans Oersted bitchy.
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Hans Christian Oersted liked to fiddle­dee­deedle,
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Measured currents with a compass needle.
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They named a unit for him, they say ­­
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Fiddle­dee­deedling sure does pay!
(Refrain)
ã 2001 Walter Fox Smith
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Directions of magnetic field lines. You must know how to use your hands
Conventional Current
Positive Charges
Right Hand
Electron flow
negative charges
Left Hand
Current flowing on a wire the magnetic field is a circle around the circle
Thumb is direction of charge flow
Fingers curl in directin of magnetic field
Check your understanding
Draw direction of magnetic field in:
Wire
b)
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Another hand rule invoves what is called a solenoid
Fonzi from happy days loved these rules
The second hand rule helps your remember the behavior of a solenoid. (a wire coiled around a core) Wrap your fingers around the solenoid in the direction of charge flow through the wire.
Your thumb represents the "North" direction of the induced magnetic field!
Use left hand
negative charges
Use right hand
conventional current
Positive charges
You try and figure out which way the charges are flowing!
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Some cool symbols
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Domain theory of Magnetism
Domains not aligned
Therefore the bar is not a magnet yet!
After stroking it with another magnet we can line up the domains thus making the bar magnetized. Watch Mr. Fotty make a magnet
This has some Interesting applications
* Being in the presence of a magnetic field can create magnets*
Hmm isn't the earth one big magnet?
Yes the earth is magnetic in fact its magnetic field looks like the one below
North pole looks like magnetic SOUTH
South pole looks
like magnetic NORTH
Therefore if the Earth is a magnet everything
that can be magnetized should be magnetized!!
we do indeed find objects like skyscrapers, ships hulls becoming magnets!
Concept Check: List two similarities and difference of electric and magnetic fields 15
Read Pages 580 ­ 592
Answer Check and Reflect
Section 12.1
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Attachments
bar magnet moving.mov
oerstedsong.mp3