CHAPTER 36:MAGNETISM
Conceptual PhysicsBloom High School
Mr. Barry Latham, M.A.Ed
36.1 Magnetic Poles
Magnets can attract and repel Like repels, unlike attracts
Forces depend on distance Inverse square rule!
Magnetic North- on a magnets, one end seeks the strongest north pole in the region
Magnetic South- on a magnets, the other end seeks the strongest south pole in the region
Always exists in pairs of N-S, even if you break the magnet in half!
36.2 Magnetic Fields
Lab 93! PhET “Magnet &
Compass 2.05”
36.3 The Nature of a Magnetic Field
Magnetic field caused by moving charges
In a magnet, the electrons are always moving
When they spin on their axis all in the same direction, they produce a magnetic field! When they spin randomly,
they don’t produce any field
The Earth gets its magnetic field from spinning too!
36.4 Magnetic Domains
Magnetic domains- areas of a material that are either aligned or unaligned to each other
There is a degree of alignment Non- not magnetic Partial- weak magnet Full- strong magnet
Creating Magnetic Domains
By putting a strong magnet near a non-magnet, it can cause the domains to align!
36.5 Electric Current & Magnetic Fields
Moving charges produce a magnetic field Section 36.3
When a current travels through a wire, a magnetic field is induced
Stronger current or more wires together Stronger magnetic field
PhET “Magnets & Electromagnets 2.05”
36.6 Magnetic Forces on Moving Charged Particles
A static charge will not interact with a magnetic field
A moving charge will be deflected by a magnetic field, though! Force is greatest when moving perpendicular to the
field lines Force is least when moving parallel
Magnetic field of Earth deflects most charged particles from the Sun and outer space
Aurora borealis is only seen near the poles, not the equator
March 5, 2010 ISS
36.7 Magnetic Forces on Current-Carrying Wires
Just as a single charge will be deflected by a magnetic field, a wire carrying a current will be deflected
The direction of the current will dictate the direction of deflection
36.8 Meters to Motors
Galvanometer Just as a compass aligns to a
magnetic field, a dial can be made to do the same thing
Ammeter Galvanometer that measures current
instead of magnetic field strength Voltmeter
Galvanometer that measures voltage instead of magnetic field
Motors
If we have an alternating current, then the magnets will spin back and forth, trying to keep up with the frequency of voltage change
http://www.youtube.com/watch?v=it_Z7NdKgmY