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