phy1020.DVI

current will produce a magnetic field inside that circuit that pointsout ofthe page, which will tend to decrease
the magnetic flux. In other words, the magnetic flux “wants” to remain relatively constant; if the moving bar
increases the magnetic flux through the circuit, then the induced current will be in a direction to decrease it,
so that it tries to stay as constant as possible.
Another way to determine the direction of the induced current is via the Lorentz force. The conducting
bar is full of free (negatively charged) electrons. As the bar moves across the magnetic field, the Lorentz force
on each electron will beFDevB; sincevis to the right andBis into the page, this meansFwill be
downward, so the electrons will move downward. The conventional current moves opposite the direction of
the electrons, so the current in the bar isupward, and the current in the circuit is therefore counterclockwise.