Download 6. Magnets and Motors

Magnet Basics
1. In your own words, what is a magnet?
2. Click on the first link magnetic fields (http://my.execpc.com/~rhoadley/magfield.htm)
and then scroll down to the middle of the page with the picture of the middle of the page.
Draw the magnetic field below.
3. Skim over this page- it gives a good introduction on basic magnetism. Write down two
facts that you didn’t know about magnetism:
3. Go back to the Magnet Basics page. When were magnets first discovered, how were
they used?
4. From the Magnet Basics page, try the third link at this web site :
http://www.newi.ac.uk/BUCKLEYC/magnet.htm Describe another story about early
magnet discoveries.
5. What is ferromagnetism and how does it work?
1. What is diamagnetism and how does it work?
Electromagnets are Attractive!
Name:
A basic electromagnet can be constructed around a long nail. Electricity flows from the
positive terminal on the battery to the negative terminal.
1. Wrap a piece of paper around the nail and tape in place.
2. Leaving a foot or so of wire free, coil an insulated wire around the length of the nail.
3. Strip the insulation off the ends of the wires. When the wires are attached to positive and
negative terminals of a battery (dry cell), the electric current around the nail will form a magnetic
field.
4. Pick up as many paper clips as you can using your electromagnet.
5. Reduce the number of coils and see if this makes a difference with the amount of paper clips
you can pick up.
6. Hook up two batteries in a series (one on top of the other) and see if this makes a difference
with the amount of paper clips you can pick up.
7. Use arrows to draw the electric current moving through the wire from the positive terminal to
the negative terminal.
Questions
1.
2.
3.
4.
5.
What purpose does the paper serve?
How does the number of coils affect the strength of the magnet?
How does the number of batteries affect the strength of the magnet?
What practical applications could electromagnets have?
Draw the magnetic field on the magnet below.
6.
An electric current flowing through a wire produces a ____________________. Coiling the
wire produces a (stronger/weaker?) _____________ magnetic field. Increasing the current
___________ the magnetic field. Increasing the number of coils ____________ the magnetic
field.
Electric
Motor Lab
Name:
In this lab you will build and test an electric motor, and describe in detail how it works. Using
what you know about magnets, electromagnets, and other research, you should be able to show
how the motor works, and predict the effects of increasing the number of batteries, magnets,
changing the size and gauge of the coils. Write the prelab including background research on the
history of electric motors, and a procedure that you will follow.
Build the motor according to the diagram below. If you have trouble making the motor work,
check with your teacher to see what adjustments may need to be made. When you are successful,
find as many ways as you can to make the motor change its direction of rotation.
Experiment with additional magnets to see if you can change the speed of the motor. For
example, hold another magnet with your fingers and bring it near the coil from above, facing the
original magnet, as the motor is operating.
Questions for Data and Discussion
1. Estimate how many revolutions per minute (rpms) your motor has.
2. Does the orientation of the second magnet make a difference? Try placing a pair of attracting
magnets atop the battery, in place of the single magnet.
3. What is the effect?
4. What other ways can you think of to change the speed of the motor? Within reason, try them.
Describe ways to change the speed of the motor.
5. Does changing the size of the wire (gauge) change the motor speed? How?
6 Describe in detail how the motor works including the function of electron flow and magnetic
fields.
7. Draw an accurate diagram of the motor, and show the electron flow and magnetic fields.