G) Generator Principle - Electromagnetic Induction
Scientific Advisors: Dr. Saul Dushman; Dr. Roman
Smoluchowski; Dr. David Harker
Prelinger
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Production Company:
Wolff (Raphael G.) Studios, Inc.
Audio/Visual:
sound, color
Creative Commons license:
Public Domain
School Blocks Youtube? Use file below.
http://www.archive.org/details/electromagnetism
This
movie is part of the collection: Prelinger
Archives
Audio/Visual: silent,
b&w
Creative Commons license: Public Domain
1831 - Michael Faraday discovered that current and voltage can be induced when a conductor (closed loop) moves within a magnetic field.
Engraving by John Cochran (1821-1865) of a portrait of Michael Faraday
in his late thirties, painted by Henry Pickersgill (1782 - 1875)
This image (or
other media file) is in the
public domain
because its copyright has expired.
© Copyright 1997,
Sergey Kiselev
and
Tanya Yanovsky-Kiselev
http://www.walter-fendt.de/ph11e/generator_e.htm
© Walter Fendt, May
8, 1998
(Note: 3 dimensional view)
Wire is perpendicular to page
If this wire is moved up or down (perpendicular to the field), maximum current (and V) will be generated.
Moved left or right (parallel to the field), no current will be generated
Toward which point should the wire be moved to induce the maximum electric potential? (voltage)
Point 1, perpendicular to field
The wire movement determines
the direction of the current
School Blocks Youtube? Use file below.
This
movie is part of the collection: Prelinger
Archives
Audio/Visual: silent,
b&w
Creative Commons license: Public Domain
How to find the direction of current
- Third Left Hand Rule
Step 1: flux lines - Out of N into S
Step 2: 4 fingers follow flux lines
Step 3: Thumb follows movement of wire (Given)
Step 4: Palm shows Push on electrons - The current direction
Ex) If the wire in the picture below is moved upward, which way will the electrons flow?
Into the page OR Out of the page?
Out of Page
Wire moved right,
Direction of induced current?
Down
List 3 factors that determine the amount of current generated when a magnet is moved is moved through closed coil of wire
St. Mary's H.S. YouTube Channel
(V) Induced voltage - also called EMF - Electromotive Force
|
V = Blv |
B - Magnetic Field Strength
l - length of conductor (in meters)
v - velocity of conductor moving through the field
Ex) Describe the direction in which the wire could be moved to produce the maximum potential difference across its ends, R and S.
 |
Magnetic field directed into the page |
To the left or right
(perpendicular to field)
Lenz's Law
St. Mary's Physics Youtube Channel
School Blocks Youtube? Use file below.
Lenz's Law - St. Mary's Physics
Lenz’s Law - The magnetic field around induced current opposes the wire motion that produced it.
Eddy Currents
School blocks YouTube? Use the link below.
SMUPhysics
November
14, 2008
All the left hand rules only work when moving charges are negative.
What do you do when
moving charge is positive?
Right Hand Rule!
Video
Enrichment
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