the wheel (when a point dips in the mercury) and the mercury. On passing current through the circuit the wheel will begin to rotate due to the action of the magnet on the current. The direction of rotation of the wheel can be determined by applying Fleming's left hand rule. While rotating and when a spoke of the wheel just leaves the mercury the circuit breaks but due to inertia of motion the wheel continues its motion and brings the next spoke in contact with the mercury thereby restoring the electrical contact. In this way rotation of the wheel continues. On reversing the direction of the current or that of the magnetic field the wheel rotates in the opposite direction. The speed of rotation depends upon the strength of the magnetic field and the strength of the current. Here mechanical energy is obtained from electrical energy. References External links Barlow's wheel designed by Eckling 1840 (German page) Barlow's Wheel - Interactive Java Tutorial National High Magnetic Field Laboratory 5H40.50 BARLOW'S WHEEL Electric motors