From current to torque
Magnetic forces on a suitably arranged current-carrying loop produce torque and rotation. Energy supplied electrically becomes mechanical work at a shaft rather than an unlimited output extracted from a permanent magnet. Torque depends on current, field and orientation, all of which matter as the structure turns.
References: [2]
Electromagnetic rotation in 1821
Following Ørsted’s and Ampère’s investigations, Faraday demonstrated continuous electromagnetic rotation in 1821. The Royal Institution’s surviving original apparatus dates from 1822, after the discovery. Distinguishing the experiment from the particular surviving object preserves the chronology of both the scientific result and its material record.
References: [1]
Maintaining continuous rotation
A simple loop’s torque changes as it turns. In a basic direct-current motor, a commutator and brushes reverse current at suitable positions so the torque continues driving rotation. Real motors use varied arrangements, coordinating electrical behaviour with rotor position to sustain motion under practical conditions.
References: [2]
Demonstration and mechanical output
A rotating demonstration differs from a machine capable of prolonged useful loading. Contacts, bearings, heat and structural stability affect implementation, while torque and speed jointly characterize mechanical output. Applying the electromagnetic principle consequently requires an arrangement suited to the intended motion and available electrical supply.