Chapter 24 – Electromagnetism *This handout follows the “Chapter 24 – Electromagnetism” PowerPoint file on my website.* Section 24.1 – Magnetism – A Generalized View There are two ends to any magnet: a __________________ and a _____________________. _____________________ and ___________________ share some similar behavior, but they are not the same! Since magnets have two poles, they are referred to as _____________________________. o Fact: No magnetic monopole has ever been discovered… yet. There are 3 main types of magnetic materials: o __________________: These materials are very strongly attracted to magnets. It is also possible to permanently magnetize these materials. Examples: Iron, Cobalt, Nickle o __________________: These materials are very weakly attracted to magnets, but cannot be made into a permanent magnet. Examples: Aluminum, Sodium. Tin o __________________: These materials are very weakly repelled to magnets. Most materials fall under this category. Examples: Silicon, Chlorine, Copper Section 24.2 – The Magnetic Field A magnetic field of a magnet point away from the ____________ pole and toward the ____________ pole. Example 24.1 – Draw the Magnetic Field Lines Draw the path of the magnetic field lines on the two magnetic dipoles using the space below.
Transcript
Chapter 24 – Electromagnetism *This handout follows the “Chapter 24 – Electromagnetism” PowerPoint file on my website.*
Section 24.1 – Magnetism – A Generalized View
There are two ends to any magnet: a __________________ and a
_____________________.
_____________________ and ___________________ share some
similar behavior, but they are not the same!
Since magnets have two poles, they are referred to as _____________________________.
o Fact: No magnetic monopole has ever been discovered… yet.
There are 3 main types of magnetic materials:
o __________________: These materials are very strongly attracted to magnets. It is also possible to
permanently magnetize these materials.
Examples: Iron, Cobalt, Nickle
o __________________: These materials are very weakly attracted to magnets, but cannot be made into a
permanent magnet.
Examples: Aluminum, Sodium. Tin
o __________________: These materials are very weakly repelled to magnets. Most materials fall under this
category.
Examples: Silicon, Chlorine, Copper
Section 24.2 – The Magnetic Field
A magnetic field of a magnet point away from the ____________ pole and toward
the ____________ pole.
Example 24.1 – Draw the Magnetic Field Lines
Draw the path of the magnetic field lines on the two magnetic dipoles using the space
below.
Section 24.3 – Magnetism – A Detailed View
So far, we can think about 3 things which behave quite
similarly:
o Gravitational Field: A Field of Presence created by
any object with _________________.
o Electric Field: A Field of Presence created by any
object with ____________________.
o Magnetic Field: A Field of Presence created by any
_____________________________.
This field propagates in a _______________ around the moving charge and has no beginning or end.
*ALL Magnetic Fields are created this way!*
Magnetism often requires a 3D perspective. So to
indicate field vectors or currents that are going into or
out of the page, we use _________ and __________.
Example 24.2 – Drawing the Magnetic Field of a Wire
Sketch the magnetic field of a long, current-carrying wire
with the current going into the paper. Draw the magnetic
field lines around the wire with the correct orientation.
Example 24.3 – What are the directions of the currents for the situations shown below?
The strength of magnetic fields are measured in ________________.
Equation #1: Magnetic Field Strength from a Current-Carrying Wire: _________________________
o is a constant and is equal to (does not need to be memorized)
Magnetic field strength and distance are _________________ proportional (
).
The Right Hand Rule for Fields only works for conventional current and the movement of positive charges, not
negative charges. We would simply us our _____________________ for negative charge movement.
How Can We Concentrate Magnetic Fields?
Imagine if you could have a loop which had a current going through it (not really possible).
Using the Right Hand Rule for Fields we would get the result indicated below.
Equation #2: Magnetic Field Strength at the Center of a Loop: _________________________
We can concentrate them even more by making multiple continuous loops as indicated below.
This coil of wire is called a ______________________.
Equation #3: Magnetic Field Strength at the Center of a Solenoid: _________________________
Example 24.4 – Current in a Solenoid
An investigator needs a uniform field, which she intends to produce with a solenoid. She takes a long
diameter tube and wraps wire along the length of it, wrapping turns of wire along a length of the tube. How
much current must she pass through the wire to produce the desired field?
How are Solenoids Like Permanent Magnets?
It was mentioned that magnetic fields can only be created using the Right Hand Rule of Fields. So how can a
permanent magnet exist when it is not hooked up to a current source???
Each atom's outer layer is made of ___________________________.
o Each of them will generate a magnetic field!
So in reality, just about everything has _________________________.
However, for most atoms, the net magnetic field is fairly close to ___________.
But, for _______________, _______________, & _______________, the multiple
magnetic fields actually agree with each other.
o This means every atom of these elements are, themselves, tiny
__________________________.
We can think of a single iron atom as being a tiny magnet indicated on the right.
𝑣
𝑣
𝑣
An arrow pointing in the direction of the net magnetic field direction
of an iron atom is call a magnetic ___________________.
Small concentrations of iron atoms which have similar facing
magnetic moments are called ___________________.
Most of the time, the net magnetic moment of a block of iron is
___________________ since the individual domains cancel out with each
other.
Why would any magnet attract to an unmagnetized piece of iron?
Even though not all of the domains in the unmagnetized piece of iron align with the permanent magnet, some of them
still do! This will cause a small attraction force.
How Would You Make a Permanent Magnet?
If you could force all the domains to align in the same direction, you would have a permanent magnet.
This can be achieved by applying a large enough current through a _____________________ wrapped around the
block of iron.
+ =
Section 24.5 – Electromagnetic Force
Since moving charges create their own magnetic field, it would make sense that if a moving charge was exposed to an
_______________ magnetic field, the interaction between the two magnetic fields would cause a ________________
to exist.
This force is always ____________________ to both the magnetic field line and motion of the charged particle.
How Can You Remember This?
We call this the ______________________________________________________________. Each finger stands for:
