Magnets
What is a magnet?
A magnet is any object with magnetic force.
A loudspeaker is a device that
changes electrical energy into sound
What is an electric motor?
An electric motor is a device
that changes electrical energy into mechanical
energy or motion.
When you bring two magnets close together they will what?
They will either repel or attract each other.
Sounds are produced when objects ____, or move back and forth ______.
What is an electric generator and how is it opposite from an electric motor?
An electric generator turns
motion into electrical energy. The
opposite of a motor, it changes
mechanical energy into electrical
energy.
What is the area of magnetic force around a magnet called?
A magnetic field
What is a microphone and how does it work?
A microphone is a device that uses a
magnet to convert sound into electrical
signals. When you speak into the
mouthpiece, a diaphragm vibrates. As the
diaphragm moves, a magnet generates
electrical signals in a wire connected to the
diaphragm. Those signals are sent to your
friend’s phone through telephone lines
What is the difference between an alternating current, and a direct current?
Alternating current flows in one
direction and then flows in the
opposite direction. The electrical
charges continuously flow back and
forth.
When the flow of a current
is always in one direction, it is
called a direct current (DC).
True or False, then explain why
Our planet is actually a giant magnet.
True! Much of the inside of Earth is made
up of melted iron.
A stereo, sends electric current to an electromagnet in the loudspeaker.
The electromagnet is attached to a diaphragm
The diaphragm is the part of the loudspeaker that vibrates to create sound. The loudspeaker also has a permanent magnet. When electric current flows, the
electromagnet is pushed and pulled by the
permanent magnet.
Explain how does a simple electric motor work like a power tool?
A simple electric motor has a power source,
a permanent magnet, a rotating loop of wire,
and a motor shaft. The shaft is a rod that
can spin and move. An electric current runs
through the wire loop, making a magnetic
field. The permanent magnet pushes and pulls
on the wire loop. This causes the wire loop to
spin. The wire loop then turns the motor shaft,
which might turn a wheel or a gear.
Explain how a compass works.
A compass is an instrument that
uses Earth’s magnetic field to help
people find directions. A compass
needle is actually a thin magnet. The
needle points north because it lines
up with Earth’s magnetic field
What is an electromagnet and how does it work?
Electromagnets can make
even stronger magnetic fields.
An electromagnet is a coil of wire
wrapped around a metal core, such
as an iron bar. When an electric
current flows through the coil,
it creates a magnetic field. This
magnetic field causes particles inside
the metal core to line up. The metal
core becomes magnetic.
Explain how a simple generator works?
A simple generator has many
of the same parts as a motor.
Mechanical energy turns the wire
loop between two magnetic poles.
The magnetic field produces an
electric current in the wire. As the
wire gets closer to the magnetic poles,
electrical charges are pushed through
the wire. The moving electrical
charges make an electric current.