Instructions
1. Starting about 3" (7.6 cm) from the end of the wire,
wrap it seven times around the paper tube. Remove
the tube (you won’t use it again). Cut the wire, leaving a 3" (7.6 cm) tail opposite the original starting
point. Wrap the two tails around the coil so that
the coil is held together and the two tails extend
centered on either side of the coil.
Seven loops
ELECTRIC MOTOR (DC)
➠
Prerequisite: A Cadet must have earned the
Electricity merit badge b e fo re b e i n g
awarded the Electric Motor merit badge.
Tail is wrapped around
the coil to hold it together, and to hold the
tail in position
Review with your counselor the safety rules and the
terms listed in the Learning section of the Electricity
merit badge.
Date Completed:Passed By:
Build a simple electric motor and explain how it works. If
badge is done as a cadre, compare the different motors
to see which motor works the best and try to discover
what makes the differences in performance.
BUILDING YOUR MOTOR
Materials needed
• 1 D alkaline battery
• 1 wide rubber band
• 2 large paper clips
• 1 rectangular ceramic magnet
• Heavy gauge magnet wire (has red enamel insulation, not plastic coating)
• 1 paper tube (toilet paper, paper towel, gift wrap,
etc.)
• Fine sandpaper
Optional
•Glue
• Small block of wood for base
1
Note: Balance is important. You might need to
put a drop of glue where the tail meets the coil
to prevent slipping.
2. On one tail, use sandpaper to remove all of the insulation from the wire. Leave about ¼" (0.6 cm) of
insulation on the end and where the wire meets the
coil. On the other tail, lay the coil down flat and lightly sand off the Insulation
insulation from
the top half of
the wire only.
Again, leave
¼" (0.6 cm)
Left Tail
Right Tail
of full insulation on the end and
where the wire meets the
coil.
3. Bend the two paper clips into the
shape shown.
4. Use the rubber band to hold the loop end to the
terminals of the battery.
5. Stick the ceramic magnet on the side of the battery
as shown.
Loop rubber band a
few times if needed
to make a snug fit.
EXPLORING: SCIENCE: ELECTRIC MOTOR (DC)
6. Place the coil in the cradle formed by the right ends
of the paper clips. You may have to give it a gentle
push to get it started, but it should begin to spin
rapidly. If it doesn’t spin, check to make sure that
all of the insulation has been removed from the wire
ends. If it spins erratically, make sure that the tails of
the coil are centered on the sides of the coil. Note
that the motor only spins the coil when it is held
horizontally.
7. Optional: For display, build a small cradle to hold the
motor in the proper position. It might also help to
bend the ends of the coil a bit (see below) so that as
it slips right or left, the bends keep it in the proper
position.
Remove the magnet from the battery. Hold the magnet next to the battery. It will spin in one direction;
but when you turn the magnet over, the wire loops
should spin the other direction. Does your hand
holding the magnet feel the work being done — the
force from moving the magnet to reverse the spin
of your electric magnet (wire loops)?
Date Completed:Passed By:
Badge Approved by:_________________________
Badge Completed on:_ _______________________
EXPLORING: SCIENCE: ELECTRIC MOTOR (DC)
2