Back in the Fields topic, we saw that a magnetic material experiences a force in a magnetic field. Copper is not a magnetic material. Hold a copper wire between a magnet's poles, and nothing happens.
Now the rig: a copper wire hangs loosely between the poles of a strong horseshoe magnet. The wire is joined through a switch to a battery. Nothing else touches the wire.
Close the switch, and a current flows through the wire. What, if anything, does the wire do?
A wire hangs between magnet poles. The switch closes and a current flows. What happens to the wire?
Here is the demonstration's whole record, kept as a table.
Copper is not a magnetic material. The field pushes on the wire only because the wire carries a current.
An aluminum rod lies between the poles of a magnet. Aluminum is not a magnetic material. A current is switched on through the rod. Does the rod experience a force?
The rod sits in a magnetic field.
The rod carries a current.
A current-carrying wire in a magnetic field experiences a force.
Yes. The rod experiences a force. This is the motor effect.
Nadia says the magnet's field pushes on the copper wire only while the wire carries a current. Is Nadia correct?
The current through the same aluminum rod is switched off. The rod still sits between the poles. Does the rod experience a force now?
The rod still sits in the magnetic field.
But no current flows in the rod.
Aluminum is not a magnetic material, so without a current the field has nothing to push on.
No. With no current, there is no force on the rod.
A current-carrying wire in a magnetic field experiences a force. Type the name of this effect.
Which statement describes the motor effect?
A wire between magnet poles carries no current and feels no force. Which change gives the wire a force?
In which situation does a wire experience the motor-effect force?