Lesson 3

Why does your motor spin? You will need your motor and a compass.
The compass is not provided in the Inventions Kit.
You can make a simple compass, if you don’t have one.

What did you do last time? electromagnet motion permanent motor coil leads PRINT the word next
to the image on the next slide.
I-Lesson 3 coi mot per lea mot ele
Why does the motor spin Last time you built a spinning motor. HOW THE MOTOR WORKS To figure this out, you will need
to locate or make a compass.

Place the coil next to the compass. Make sure the coil DOES NOT align with the north pointing needle.

Make sure that the SANDED side
of each lead is in contact
with the paperclips.

What happens to the compass needle? Why does this happen The compass needle
should move and point at the coil.

This shows that WHEN ELECTRICITY
IS FLOWING through the COIL,
the COIL is an electromagnet. Click to make a compass. Click for answer. Click to watch: Test what happens when
the ENAMELED side of each lead
is pressed against the paperclips.

What happens
to the compass needle now?

Why Click for answer. When the enameled side of the leads
press against the paperclips,
no electricity can flow through the coil.

Now, the coil is NOT an electromagnet.
The coil will NOT move the compass needle.
The compass will point north. This is only half of the story! When the COIL is an electromagnet,
it turns to line up with the bar magnet below
and the motion begins.

Just as this happens, the enameled side
of each lead touches the paperclips.
Electricity STOPS flowing through the coil.
The electromagnet is OFF, but the coil is moving
and it keeps on moving (inertia)
long enough for the cycle to repeat.

So half the time the coil is an electromagnet that moves
to line up with the permanent magnet below and half the time
the coil is just coasting. You have made an inertial HALF motor. Click to watch: Putting it Together How does the ON again,
OFF again of the coil create motion A force is . . .
 FORCE a push or a pull The FORCE
that makes your motor move is THE MAGNETIC
PUSH / PULL
between the permanent magnet and the coil,
when it is an electromagnet. INERTIA You have likely experienced INERTIA. Why does the coil
keep on MOVING
when the coil
is no longer an electromagnet INERTIA!
An object in motion
stays in motion
unless acted upon
by an unbalanced force. You made HALF a motor.
Half the time your coil is an electromagnet
and half the time it is just coasting -- INERTIA! The sanding pattern on your coil,
turned it into a SWITCH.

Half the time the coil conducts electricity
and the other half of the time it does not! You made
an inertial
HALF motor. You have
a DC electric motor
in your kit. It works on
very similar
principles! How a DC Motor Works In your motor what is the
FORCE that turns the coil
toward the permanent magnet Once in motion,
why did your coil
STAY in motion What turns a coil
into an electromagnet What happens to a bulb
when it is connected
to your motor and battery 1 2 3 4 5 Why does the bulb flicker It flickers. It is the MAGNETIC force (push/pull) between
the permanent magnet
and the coil, when it is
an electromagnet. INERTIA! Electrical current The way you sanded
the coil makes it act
like a switch. ON. OFF.

Introduction

Lesson 1

Lesson 2

Lesson 3

Resources

Lesson 4

Lesson 5

Lesson 6

Lesson 7

Lesson 8
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