Electromagnetic induction, generators, and transformers

Magnetic flux measures how much magnetic field passes through a loop of wire. Faraday's law says that a changing magnetic flux induces a voltage in the loop, and the faster the flux changes, the larger the voltage; if the flux through the loop stays constant, nothing is induced. The flux can change because a magnet moves, the loop moves or rotates, or the field itself grows or shrinks. Lenz's law gives the direction: the induced current flows so that its own magnetic field opposes the change that caused it, a consequence of conservation of energy. A generator uses induction by rotating coils in a magnetic field, turning mechanical energy from steam, wind, or falling water into electrical energy, and it naturally produces alternating current (AC). A transformer uses induction to change an AC voltage: alternating current in a primary coil creates a changing magnetic field in an iron core, which induces a voltage in a secondary coil. In an ideal transformer, the ratio of the two voltages equals the ratio of the numbers of turns in the coils. Power companies step voltage up for long-distance transmission, which lowers the current and the energy lost as heat in the lines, then step it down for homes. Transformers do not work with steady direct current, because a steady current makes no changing field.

This explanation is AI-generated and can occasionally be wrong. 🚩 Report