7 electrical measuring instruments, electric engines
7 electrical measuring instruments, electric engines.docx
1: Building an electric motor.
a short knitting needle through a large cork.
pins in one end of the cork as shown, to make a simple commutator.
wind round the cork about 30 turns of thin insulated copper wire, starting of
one pin and finishing at the other. It helps if you can cut channels in the
cork to take the wire.
the insulation off the ends of the wire (using emery paper or a knife). Wrap
each end of the wire round a pi, making good electrical contact.
pairs of long pairs into a baseboard to support the axle at each end.
the insulation from the ends of 2 wires and use drawing pins to hold them in
position so that they just touch the commutator.
plasticine to support magnets on each side of the coil (with opposite poles
the wires to a 2 V or 4 V supply and give the coil a flick to start it.
GROUP 2:How to Build a Simple Electric Motor
Part 1: Winding the Coil.
1.Tape together four pencils. Tape the pencils in a two by two cluster.
This will give you something solid to wrap your coil around. You can substitute
the pencils for a cylinder that’s roughly half an inch in diameter.
2.Wrap wire around the pencils. Once you have the pencils taped or find a
suitable cylinder, begin wrapping your wire around it tightly. Start in the middle
of the wire and wrap the coil fifteen times toward one end and fifteen times
toward the other. Once you have finished wrapping the coil, remove the pencils
from the middle. This will leave you with two loose leads at either end of the
3.Loop the loose ends around the coil. Wrap the loose ends around either side of
the coil three or four times. This will help keep the coil wound tightly. Point
the remaining loose ends straight out away from the coil.
2: Connecting the Battery.
1.Secure the battery.
Use tape or clay to hold the battery in place
on a flat surface like a tabletop or desk. This will allow you to connect it to
the coil without having to hold it with your hands. Make sure the battery is
laying on its side so that you can easily reach both terminals.
2.Strip the ends of the coil wire. Use wire strippers to remove the
insulation on either end of the wire, but only one half of the insulation, such
that the bare wire will be connected to the circuit only half the time. These
leads will connect to the battery and allow current to flow through the coil.
If you sand the wire all the way around, the wire will heat up or move back and
forth, and the motor will not work.
3.Slide each end through the eye of a needle. A needle makes the perfect holder for the
wire leads. Insert each end into the eye of a separate needle. You can also
bend two paper clips (one for each side) to make a holder.
4.Tape the needles to the battery terminals. Once you have the wire in both needles,
it’s time to hook your wire up to the battery. Tape one needle to the positive
side of the battery (marked with a “+”). Tape the other needle to the negative
side of the battery (marked with a “-”).
3: Introducing the Magnet
1.Bring a magnet close to the coil. Once a current is flowing through the
coil, it can interact with a magnet. Either hold the magnet close to the coil,
or tape it to the battery right underneath the coil. The closer the magnet is
to the coil the stronger it will interact.
2.Spin the coil. See what happens when you spin the coil. Depending on
the direction the current is flowing and the side of the magnet that is
interacting with the coil, the coil may continue to spin or may not. If the
coil does not keep spinning, try spinning the other direction.
3.Experiment with different methods. Different variations will give you
different results. The coil may spin faster, slower, or not at all if you
change something. Try moving the magnet closer to or further from the coil,
pick a stronger or weaker magnet, or use the other side of the magnet. These
variations are a fun way to understand the forces in an electric motor.