EMI - Rotating Conductor

Magnetic Field Positive Negative

Animation shows a conductor rotating about a vertical axis in a magnetic field directed parallel to the axis with its end sliding on smooth circular conducting rail. (The plane of motion is horizontal). A cell is connected through a resistance between the axis and the rail. When the switch is closed, the current through the conductor causes it to experierence a force that causes rotation of the conductor. As the conductor rotates the emf induced in it opposes the exteranal cell and causes the current to decrease. This in turn causes the torque on the conductor to decrease. So angular velocity exponentaily increases and current drops to zero exponentially. The condcuctor then rotates at a constant terminal speed. The blue curve shows the current in the conductor.
The red curve represents the magnitude of angular velocity.
The equations for induced emf, current, torque and terminal angular velocity are