Transcript Magnetism - Scoilnet

Magnetism
What is magnetism?
Force of attraction or
repulsion due to electron
arrangement
Magnetic forces are the
strongest at the poles
Magnets have two poles:
North and South
Magnetic poles and fields
Magnets always have two poles
If a magnet is cut it will still have
two poles
Like magnetic poles repel
Unlike magnetic poles attract
A magnetic field is the area in
which magnetic forces act
Questions
What two forces are involved in
magnetism?
Which subatomic particle accounts
for magnetism?
Explain the interaction between
magnetic poles when they are
close together.
Magnetic materials
Natural magnets have
naturally occurring magnetic
properties ex: LODESTONE
(magnetite)
Temporary magnets
Easy to magnetize
Lose their magnetism
quickly
Ex: Soft iron
Permanent magnets
Hard to magnetize
Stay magnetized longer than
temporary magnets
Ex: alnico (cobalt, nickel,
aluminum)
Questions
How is a temporary magnet
different from a permanent
magnet?
Give an example of a natural
magnet.
Earth’s magnetic properties
Gilbert was a scientist that showed
that the Earth behaves as a magnet
The Earth’s magnetic field is
strongest at the poles
Earth’s magnetic field is called the
magnetosphere
Compasses
Compasses are used to determine
direction
Compass needles are magnetized
and respond to the magnetic field
of the Earth
Compasses point to the
MAGNETIC POLES OF THE
EARTH
Other sources of magnetism
Magnetic fields of the Earth
and other planets are related
to their cores
The sun is a source of a
magnetic field
Questions
Which scientist described the
Earth’s magnetic properties?
Name the devices used to
indicate geographic direction
based on the Earth’s magnetic
field.
Questions
What is the name of the
Earth’s magnetic field?
Where is the Earth’s
magnetic field the strongest?
Magnetic variation
Magnetic poles of the Earth
are different from the
geographic poles of the
Earth
Magnetic Induction
Process by which materials
can be magnetized
What affects magnetic
properties?
Spinning electrons cause some
metals to have magnetic properties
Magnetic domains are groups of
arranged magnetic fields
Dropping,hammering or heating a
magnet will cause a magnet to lose
magnetic properties
Electromagnetism
Discovered by Oersted (scientist)
Relationship between electricity
and magnetism
Electromagnets
Temporary magnets
Magnetism can be turned on and
off
Made by wrapping wire around a
piece of iron and sending a current
through the wire
Magnetic field is in the same
direction as the electric current
Increasing the strength of
electromagnets
Increasing the voltage or
current
Increasing the number of
loops of wire
Questions
Explain magnetic variation.
What is electromagnetism?
Who discovered
electromagnetism?
Name two ways to increase the
strength of an electromagnet.
What type of magnet is an
electromagnet?
Electric motors vs. generators
Electric motors convert
electricity to mechanical
energy in order to do work
Generators convert
mechanical energy to
electrical energy
Transformers
Used to increase or decrease
voltage
Made of primary and secondary
coils
Two types of transformers:
“Step-up” (increase voltage)
“Step-down”(decrease voltage)
Questions
How is a generator different
from an electric motor?
Name two types of
transformers.
How is a step-up transformer
different from a step down
transformer?
What are the two parts of a
transformer?