LIMIT SWITCHES

The battery provides power for the pump, which moves water from the lower tank to the upper tank. 
Whe the upper tank is full, a limit switch turns off the pump.
The switch is activated when the float rises to a certain level.
When the water level goes down, the switch returns to its original position and the pump turns on again.

CAM SWITCH CONTROLLER

The device on the side of the pulley in the picture above is called a cam. The shape of this device allows us to control the moment and duration of an activity.

ELECTROMAGNETIC CONTROL SYSTEMS

An electromagnetic control system activates the various parts of a machine, at the right moment and for the right amount of time, ensuring that the machine functions properly.

RELAYS

A relay is an electromagnetic component that works as a switch. When electricity passes through the coil, it acts like a magnet. When electricity stops flowing, the moveable contact goes back to its original position.

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.

ELECTROMAGNETIC GENERATORS

There are two types of generators, depending on the type of current that is produced:
-Dynamos: They produce direct current. A dynamo consists of a magnet and a rotary coil. The coil is located between the two poles of the magnet. The ends of the coil have two semi-circular conductors, which form the commutator.

-Alternators: They produce alternating current. They are identical to a dynamo, except for the commutator, which consists of two metallic rings connected to carbon brushes. Instead of direct current, this produces alternating current.

ELECTROMAGNETIC MECHANISMS

Electromagnetic mechanisms are devices that can convert movement into electricity or vice versa. They use electromagnetic phenomena to produce electricity or convert it into mechanical energy.

SOUND

We can transform electric current into sound by using electromechanical devices, such as bells and buzzers. Some of these devices are based on the piezoelectric effect, or the ability of some materials to change shape whe electricity is applied to them.

ELECTROMAGNETIC EFFECTS

The scientist Michael Faraday discovered that electricity could be generated by using a magnet and an electrical conductor.
This principle allow us to build dynamos and alternators.
To generate an electric current with a magnet, we can move the conductor or we can move the magnet.

    

(ALTERNATOR).

LIGHT

There are various ways that electricity can be used to produce light.
For example, we can heat a conductive filament or energise the electrons of a fluorescent gas.
We can use also an electronic device called a light-emitting diode (LED)

Incandescent bulbs.
When an electric current passes through the metallic filament of a light bulb, it produces light. This phenomenon is called incandescence.

Fluorescent tubes.
Inside a fluorescent tube, there is a metallic filament, normally made of tungsten. There is also an inert gas, such as argon, and a samall amount of mercury. When an electric current passes through the filament, electrons are emitted into the inert gas. 
These react with the mercury, creating invisible, ultraviolet light.
Then the phosphor coating inside the tube transforms the ultraviolet light into visible light.
Fluorescent tubes contain a number of toxic substances, such as phosphor and mercury.

Light-emitting diodes (LED)
A light-emitting diodes (LED) has layers of semiconductor materials. When electricity is applied to the LED, the electrons and holes cross over into the active layer, where they combine and produce photons, or particles of light.