6. Electromagnetic mechanisms.

Electromagnectic mechanisms are devices that can convert movement into electricity or vice versa. In other words, the use electromagnetic phenomena to produce electricity or convert it into mechanical energy.

6.1. Electromagnetic generators.
Electromagnetic generators transform mechanical energy into electricity. There are two types of generators, depending on the type of current that is produce. Generators that produce direct current are called dynamos, and those that produce alternating current are called alternators.

DYNAMOS.
A dynamo consists of a magnet and a rotary coil. The cail is located between the two poles of magnet. The ends of the coil have two semi-circular conductors, which form the commutator. When electricity is applied to the coil, it rotates and begins to generate direct current in the col.


ALTERNATORS.
A simple alternator is almost identical to a dynamo, except for the commutator, which consists of two metallic rings connected to carbon brushes. Instead of dirrect current this produces alternating current.

6.2. Electric motors.

An electric motor is a device that can transform electrical energy into movement. It uses the forces of attraction and repulsion between a magnet and an electrically charged wire.


6.3. Relays.
A relay is an electromagnetic component that works as a switch. When electricity passes through the coil, it acts like a magnet. The coil attracts a moveable metal contact towards another fixed contact. When the electricity stops flowing, the moveable contact goes back to its original position.
Relays may have a single circuit with one moveable contact. The may also have two or four circuits, in wich case they are called two- or four-pole relays.