12.1 - Intro to Magnetism

Question 1

A ______ is a material or object that
produces a magnetic field.

Answer 1

magnet

Question 2

This magnetic field is invisible but can exert a
force on other __________ materials
(like iron) and can __________ other
magnets.

Answer 2

ferromagnetic; attract or repel

Question 3

Most materials will respond at least a _____ __
to a magnetic field, but only a very small bit.

Answer 3

little bit

Question 4

Materials that respond very strongly to a
magnetic field are called ________.

Answer 4

ferromagnetic

Question 5

examples of ferromagnetic materials

Answer 5

iron, nickel, cobalt

Question 6

Every magnet has a _________ pole

This is known as the Law of ___________

Answer 6

north and south; magnetic poles

Question 7

All magnetism is, at the smallest scale,
due to the motion of _______.

Answer 7

electrons

Question 8

Electrons spin (like the earth) and this
sets up ______ _____ at the atomic
level.

Answer 8

magnetic poles

Question 9

Groups of atoms with the same magnetic
orientation form ________ within a
substance.

Answer 9

domains

Question 10

These domains are like tiny little _______ of their own.

Answer 10

magnets

Question 11

A _______ ______ is created when all (or many) of the domains inside a material are aligned the
same way.

Answer 11

permanent magnet

Question 12

domains in non-magnetic materials

Answer 12

no domains

Question 13

domains in magnetic materials

Answer 13

domains but not lined up

Question 14

domains in a magnet

Answer 14

domains and all lined up

Question 15

Because magnets are essentially made
up of tiny ___________ ______, every
time you cut a magnet in two you get
____ ____ _______ – both will have a
north and south pole.

Answer 15

microscopic magnets; two new magnets

Question 16

Each time you cut the magnet, you get ______ ______ magnets.

Answer 16

smaller, weaker

Question 17

If you have a ferromagnetic material, such as
iron, you can use it to _______ a magnet by
putting it within a magnetic field.

Answer 17

create

Question 18

Placing the ferromagnetic material within a magnetic field will cause all the domains to align, which will cause the material to become a _______.

Answer 18

magnet

Question 19

Magnets can become ‘___________’
or lose their magnetic strength by:

Answer 19

de-magnetized; heating, hitting, dropping

Question 20

Any of these methods cause the domains
inside the magnet to become _________,
which is why the magnet becomes
‘de-magnetized’.

Answer 20

disordered

Question 21

A ________ _____ is the space around a magnet
where a ______ _____ can be felt. It is very
similar in theory to an electric field.

Answer 21

magnetic field; magnetic force

Question 22

The magnetic field around a magnet is
strongest at the _______.

Answer 22

poles

Question 23

The north pole and the south pole of the same
bar magnet are in general, _________ _____.

Answer 23

equally strong

Question 24

Lines of magnetic force show how the ________ ______ acts around the magnet. The force is ___________ at the poles (where the lines are close together) and weaker the further out you go.

Answer 24

magnetic force; strongest

Question 25

When a compass is places upon a
line of force, the compass needle
always points …

Answer 25

along the line

Question 26

The north pole of the compass is directed toward
the _____ ___ of the magnet.

Answer 26

south pole

Question 27

The direction of a line of force is defined as the
direction in which the _____ ___ of a compass points when placed along that line.

Answer 27

north pole

Question 28

When drawing Magnetic Field lines,
remember:

Lines go from ____________ outside the
magnet

Lines go from __________ inside the
magnet

Lines never cross

Answer 28

North to South; South to North

Question 29

Lines of force that act in the same direction will
make the magnetic force ________

Answer 29

stronger

Question 30

Lines of force that act in the opposite direction
will make the magnetic force ______.

Answer 30

weaker

Question 31

Parallel fields from two different magnets
show us that there is a __________.

Answer 31

repulsion

Question 32

Opposite fields from two different magents
show us that there is an ___________.

Answer 32

attraction

Question 33

The Earth has a magnetic field, which can
be detected by a compass.

The magnetic field around the earth is
actually not the way we would think of it.
The geographical North pole actually
works the same way as the _______ _____ of
a magnet.

Answer 33

south pole

Question 34

Describe the importance of the compass to navigation.

Answer 34

The compass is an important tool in navigation
because it enables navigators to measure the
direction in which they are travelling relative to
magnetic north.

This is especially valuable at night
or when the sky is overcast and the Sun cannot be
used to estimate direction

Question 35

How would moving the magnetic north pole of Earth to a point on the equator change navigation using a compass?

Answer 35

If the magnetic north pole were moved to a
point on the equator, navigation would become
very difficult.

Compass needles would point toward the new pole location on the equator, so all directions shown on the compass would be inaccurate.

Also, compasses would be difficult to use near the new poles on the equator because the direction the needle points would change a lot.

It would probably be easiest to redefine north and
south in terms of the new magnetic poles.

Question 36

Suppose Earth had no magnetic field.
(a) How would the northern lights be affected?

Answer 36

If Earth had no magnetic field the northern
lights would not exist because they are caused by
charged particles interacting with Earth’s magnetic
field.

Question 37

Suppose Earth had no magnetic field.
(b) What would happen to animal navigation?

Answer 37

If Earth had no magnetic field, animals that use
the magnetic field to navigate when migrating
might lose their way and not reach their
destination.