Investigation 4.1 Electric Motors

Electromagnetism and Electric Motors

​A Review of Investigation 4.1

BUT First...

Some questions to reivew what we know!

Multiple Choice

What is the relationship between electricity and magnetism?

• electromagnetism

• magnetricity

• magnetocircuit

• there is no relationship

Multiple Choice

Magnets can...

• attract one another

• repel one another

• both attract and repel one another

Multiple Choice

An electric current running through a wire in a complete circuit creates _____________.

• a magnetic field

• an electric field

• a thermal field

• a light field

Not so bad, right?!

On to Investigation 4.1!

In class, we looked at three main parts of the dissected motor:

1) Casing

2) Shaft Component

3) Cap

​The metal casing contains the two permanent magnets of the motor.

Casing

The shaft component contains the shaft, the electromagnets and the commutator.

Shaft Component

​The cap contains the two brushes which connect to the outer wires.

Cap

Multiple Choice

Which part of the electric motor contains the permanent magnets?

Multiple Choice

Which part of the electric motor contains the commutator?

Multiple Choice

Which part of the electric motor contains the brushes?

Multiple Choice

Which part of the electric motor contains the electromagnets?

Keep it up!

The term for those flat ends of wire is brush.

The current runs in through the wires from the battery, through the brush, to the commutator.

The current passes through contact between the brush and commutator.

The commutator has three gaps.

Depending on where the commutator is in the rotation, it’s touching only two contact points (brushes), so two parts will receive the electric current and one part will not.

Two sections of current will pass through the commutator to the electromagnets and one will not at any given time!​

​On

​On

​Off

Only two sections of the electromagnet are turned on at one time; when turned on, these sections repel from the permanent magnets in the case, causing the shaft to rotate

​On

​On

​Off

As soon as the shaft rotates, the commutator is in a new position and one section will turn on while another turns off

The cycle will continue, turning the shaft over and over again.

Multiple Choice

Electric motors are devices that convert _____ energy into  _____ energy.

• electrical; mechanical

• mechanical; electrical

• chemical; potential

• mechanical; kinetic

Multiple Choice

How many brushes are there in the motor cap?

• One

• Two

• Three

Multiple Choice

How many gaps are there in the commutator?

• One

• Two

• Three

• None

Multiple Choice

How many electromagnets are there in the motor?

• One

• Two

• Three

• None

Multiple Choice

How many electromagnets can receive electric current and "turn on" at any given time?

• 1 out of 3

• 2 out of 3

• 3 out of 3

• none of the electromagnets

Multiple Choice

What causes the shaft to spin?

• The electromagnets that are turned on repel the permanent magnets in a cycle

• The electricity runs through the shaft and becomes mechanical energy

• The permanent magnets rotate around the shaft

End of review!