The rig again: the same magnets, and the same wire perpendicular to the field. This time only the current changes. The power supply's display sets the current.
With a small current, the wire experiences a small force.
The current is turned up. The magnets have not changed. The force gets bigger.
The current is turned up further. The force grows again.
A rig's current is turned up. Nothing else changes. What happens to the force on the wire?
A rig's current is turned down a little. Nothing else changes. What happens to the force?
One boundary case matters. The current is turned down to zero — and the force disappears. No current means no motor-effect force, however strong the magnets.
A student says zero current means zero force, even between very strong magnets. Is the student correct?
Two rigs use identical magnets and wires. Rig J's wire carries 2 A; rig K's wire carries 5 A. Which wire feels the bigger force?
A rig's current is increased, with nothing else changed. What happens to the direction of the force on the wire?
A demonstration wire's jump is too small to see. The magnets and the wire must stay as they are. Which change makes the force bigger?