Download Electromagnetism PPt

Draw a diagram that
shows the magnetic
fields that result when
like poles of two
magnets are close to
each other when
unlike poles are close.
Use lines to show the
magnetic fields that
result from these
situations.
Warm Up:
Current Can Produce
Magnetism
Now, you will learn
Before, you learned



Electric current is the
flow of charge
Magnetism is a force
exerted by magnets
Magnets attract or
repel other magnets



How an electric
current can produce
a magnetic field
How electromagnets
are used
How motors use
electromagnets
Electromagnetism
 Electromagnetism
– magnetism that
results from an electric current. When a
charged particle moves, it produces a
magnetic field.
 Because an electric current consists of
moving electrons, a current in a wire
produces a magnetic field. Increasing
the amount of current in the wire
increases the strength of the magnetic
field.
Magnetic Field of a Wire
 The
direction of current
Determines the direction
Of the magnetic field
Electromagnetism
 How
is a coil of wire that carries a current
similar to a bar magnet?
Electromagnet
A
magnet made by placing a piece of
iron or steel inside a coil of wire. As long
as the coil carries a current, the metal
acts as a magnet and increases the
magnetic field of the coil. When the
current is turned off, the magnetic
domains in the metal become random
again and the magnetic field disappears.
Electromagnet
 By
increasing the number of loops in the
coil, you can increase the strength of the
electromagnet.
Uses of Electromagnets
 Electromagnets
can be turned on and
off, and have more uses than permanent
magnets.
 Electromagnets store information on a
computer
 Electromagnets pick up and dumb
recycling at a dump
 Magnetic strips of credit cards
 Motors
Review
 1.
Explain how electric current and
magnetism are related.
2. Describe three uses of an electromagnet
3. How does an electromagnet differ from a
permanent magnet?
Fill in the blanks with words from the box.
cars
fans
magnetic
coils
generator
motor
currents
hydroelectric
spins
electromagnetism
kinetic
turbine
Magnetism and electricity are connected in a way that is
very useful to people. Magnetic fields can be used to
generate electric _________________ and electric
currents can be used to generate
_________________ fields. This connection
between magnets and electricity is called
_________________. How does this work? As
Hydroelectric generators convert
the kinetic energy of water flowing
downhill into electricity.
a_________________ of wire spins in a magnetic
_________________, a current flows through it.
A device that uses a coil of spinning wires in a magnetic field to make electricity is
called a _________________. A _________________ power plant, for
example, uses the energy of flowing water to generate electricity. As water flows from a
high place to a low place, it pushes on _________________ blades causing them to
spin. Coils of wire are attached to the spinning turbine and placed next to magnets. As
the coil _________________ in the magnetic field, electric current flows through
the wires. In short, the _________________ energy of water is transformed into
electrical energy.
This process can be reversed to produce an electric _________________. An
electric current through a coil of wires in a magnetic field will cause the coil to start
spinning. This coil is attached to an axle, which can be used to move something else
such as a wheel or a blade. _________________ and toy cars are examples of
devices that use an electric motor to generate motion.