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Name________________________________
Block ________________________________________
Now, we will learn: (3 main ideas on top of the page)
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An electric current produces a magnetic field
Like many discoveries, the discovery that electric ___________________ is related to
_________________ was unexpected. In the 1800s, a Danish physicist named Hans Christian
Oersted (UR-stehd) was teaching a ___________ class. Oersted used a _______________ and
_______________ to demonstrate some properties of ____________________. He noticed that as
an _____________________________ passed through the ______________, the needle of a
nearby _________________ moved. When he turned the __________________ off, the needle
__________________ to its original direction. After more experiments, Oersted confirmed that
there is a _______________________ between magnetism and electricity. He discovered that an
___________________________________ produces a ____________________________.
Electromagnetism
The ___________________ between electric ______________ and ________________ plays
an important role in many ______________ technologies. ______________________ is
magnetism
that
__________________
__________________________
such
as
from
an
an
electric
current.
___________________
When
a
moves,
it
_______________ a magnetic field. Because an __________________________ generally
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consists of ________________ electrons, a ________________ in a wire _______________
a magnetic field. In fact, the _____________ acts as a ______________. Increasing the
________________ of current in the wire ________________ the strength of the magnetic
field.
Copy the diagram showing how a magnetic field surrounds a current carrying wire
The ________________________ of a wire actually forms the ___________ of a _________
around the wire. The ____________________ of the ________________ determines the
__________________ of the magnetic field. If the __________________ of the electric current is
___________________, the magnetic field still exists in circles around the wire, but is
__________________. If the wire is ________________ into a ______________, the magnetism
becomes _________________________ inside the loop. The field is much ________________ in
the _____________ of the _____________ than it is around a straight wire. If you _____________
the wire into a _______________, the magnetic force becomes ___________________ with each
_____________________________
of
wire
as
the
magnetic
field
becomes
more
__________________________.
Copy the diagram showing the magnetic field with a coil
Why is the magnetic field stronger when we wrap the wire into a coil, where
would you expect to have the strongest magnetic field?
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How is a coil of wire that carries
a current similar to a bar magnet?
A coil of wire with charge flowing
through it has a magnetic field that is
similar to the magnetic field of a bar
magnet. Inside the coil, the field
flows in one direction, forming a
north pole at one end. The flow
outside the coil returns to the south
pole. The direction of
the electric current in the wire
determines which end of the coil
becomes the north pole.
Making an Electromagnet
Recall that a piece of ____________ in a strong magnetic field becomes a ______________ itself.
An _______________________is a magnet made by placing a _____________________ or
_________________ inside a ______________ of wire. As long as the ____________ carries a
__________________, the metal acts as a magnet and __________________ the magnetic field
of the coil. But when the current is turned _________, the magnetic ______________ in the metal
____________________________ again and the magnetic field __________________.
How can Jimmy
increase or decrease
the strength of the
electromagnet?
Jimmy
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Uses of Electromagnets
Use the following mind map to identify 4 main ideas for the uses of electromagnets:
Uses for electromagnets
Motors use electromagnets
Because magnetism is a ______________, magnets can be used to ______________________.
Electric motors _______________ the ________________ of an electric current into
________________ by taking advantage of the _______________________ between
____________ and ___________________. There are hundreds of ________________ that
contain ________________ motors. Examples include power ______________, electrical
_______________ appliances, and the small ____________ in a computer. Almost anything with
_______________ parts that uses _______________ has an electric ______________.
Motors
Label the parts of the DC (Direct Current) motor
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Label the indicated parts:
What is a commutator?
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Describe how a basic electric motor works:
Why does an electric motor have to use an electromagnet rather than a permanent magnet to
rotate the shaft of an electric motor?
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Uses of Motors
There are many uses for electric motors.
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Read the section on "Uses of Motors" and try to pick out 5 different uses for electric
motors:
1. _________________________________________
2. _________________________________________
3. _________________________________________
4. _________________________________________
5. _________________________________________
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Now try to think of 3 more on your own:
1. _________________________________________
2. _________________________________________
3. _________________________________________
Energy (this part is not in the book) – you must use your head.
Energy cannot be created nor can it be destroyed – it can only change forms
Electrical Energy – energy in the form of electricity that has the potential to do work
Kinetic Energy – the energy of motion
Question: How does a motor turn electrical energy into kinetic energy?
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