An eddy current is an electrical current induced in a piece of metal due to the relative motion of a nearby magnet. Any time a magnet passes a metallic object, its magnetic field induces an electric current, which swirls around near the surface of the metal like an eddy in a river. This electric current creates its own magnetic field, which opposes the motion of the magnet.
Eddy currents are responsible for some remarkable effects when properly utilized. The opposing magnetic fields produced by eddy currents can result in marked slowing of the motion of a magnet, even when it is otherwise in free fall. A strong magnet dropped through a thick copper tube, for instance, falls far more slowly than it would under the influence of gravity alone.
This effect is only observed when magnets move near metals, not nonmetals. This is because of the nature of the metallic bonds in solid metals, which allow for the relatively free flow of electrons between atoms. This is the same property that is responsible for the generally good electrical conductivity of metals. Because of this property, it is relatively easy for magnetic fields to start an electric current, which is just another way of saying electron movement.Learn More
Voltage, or electrical pressure, in a system produces a proportionate amount of current when placed across electrical resistance. Ohm's law indicates that 1 volt passed through 1 ohm of resistance produces 1 ampere of current, or electrical flow. Voltage and current, therefore, have a direct relationship most of the time.Full Answer >
Transformers have two sets of wires wound around an iron core, and they use electromagnetic induction to increase or decrease electrical current. The primary wires magnetize the iron after the application of current, and the secondary wires use the magnetic induction to create an output current. The increase or decrease of output current depends on how many times the input and output wires wind around the core.Full Answer >
When salt dissolves in water, negative and positive ions are pulled in opposite ways by an electrical field, which creates an electrical current. The ions that are created include sodium, which has a positive change, and chloride, which has a negative charge.Full Answer >
Tall buildings have lightning conductors to help transport the electrical current from a lightening strike to the ground safely. This protects the structure's electrical equipment and the materials used within the building.Full Answer >