1 min
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Electric motors are inside all kinds of ordinary devices, using a power source to make motion. So what makes the motor go 'round?
The basis of an electric motor is:
a spark plug
a magnet
a battery

In an electric motor, a central magnet spins, creating motion. This motion is behind everything from the turning wheels on a toy car to the starter motor in a real car's engine.

A motor's motion comes from which property of magnets?
Like poles repel each other.
Opposite poles attract each other.
both A and B

Inside a motor, the attraction and repulsion of magnets keeps a bar spinning. This creates rotational motion.

The six basic parts of a simple two-pole motor are:
the armature, the commutator, the brushes, the axle, a field magnet and a DC power supply
the armature, the brushes, the battery, the axle, the anchor and a field magnet
the commutator, the brushes, the casing, a DC power supply and the wires

If you dismantle the motor inside a small toy, you'll find a power source and magnets. At the heart of the motor are the armature, commutator, brushes and axle. These parts work together to make things move.

A motor's armature acts as:
a rotor
an anchor
an axle

The rotor, or armature, is an electromagnet. When electricity moves through the coils of the armature, it creates a magnetic field, and the rotor spins.

When a small motor turns on, the armature spins because of:
gravity
magnetism
inertia

The poles of a motor's field magnet attract and repel the poles of the armature. The field magnet can be an electromagnet, but many small motors use permanent magnets to save power.

What two parts of an electric motor are responsible for changing the direction of the current?
the commutator and the rotor
the axle and the brushes
the commutator and the brushes

A commutator is basically a switch that comes into contact with the brushes in the motor. At just the right moment, the switch will flip. This ensures that the motor produces steady motion

Which part of the motor holds the armature and commutator in place?
wires
battery
axle

The motor's axle runs through the armature and commutator. In addition to holding them in place, it allows the armature to spin, creating motion.

What part of the motor transfers power from the battery to the commutator?
wires
brushes
poles

A small motor's brushes are pieces of springy metal that come into contact with the commutator, delivering power.

Why do most rotors in an electric motor have three poles instead of two?
It prevents the motor from getting stuck.
It prevents the commutator from shorting out the battery.
both A and B

Imagine a bar magnet suspended between the north and south poles of a horseshoe magnet. Usually, the attraction and repulsion between the poles will cause the bar to spin. But if the bar was exactly horizontal, it might get stuck in one position. A three-pole rotor keeps this from happening. A two-pole motor would also continually short out, possibly burning out the battery.

Which of these kitchen appliances does not have an electric motor?
blender
water filter
refrigerator