7)ELECTROMAGNETIC CONTROL SYSTEM

The sistem which you can watch down is completely automatic.The cam on the side of the puley pushes the two metal contacts together for a short period of time.This happens once every time the pulley makes a complete circle, producing an intermittent light.

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

CAM SWITCH CONTROLLER

The device on the side of pulley in the picture above is called cam.The shape of this device allows us to control the moment and duration of an activity, such as the running of a motor or the illumination of light bulb.

LIMIT SWITCHES
The picture below shows an electrical control system for a water tank.The battery provides power for the pump, which moves water from the lower tank to the upper tank.When 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.There are two types of limit switch:

In this video you will learn:What is a limit switch

https://www.youtube.com/watch?v=P7y0TSsAlFw

6)ELECTROMAGNETIC MECHANISMS

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

ELECTROMAGNETIC GENERATORS

Electromagnetic generators transform mechanical energy into electricity.There are two types of generators, depending on the type of current that is produced.Generators that produce direct current are called dynamos, and those 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 coal is located between the two poles of the magnet.The ends of the coil have two semi-circular conductors, which form the commutator.These conductors are attached to carbon brushes, which in turn are connected to electrical wires.When electricity is applied to the coil, rotates and begins to generate direct current in the coil.

A simple dynamo with only one coil produces a pulsating direct current.If the dynamo has two or more coils at different angles, a more constant flow of direct current is produced.

In this video, we can watch the functioning of a dynamo: https://www.youtube.com/watch?v=RMM-TVtmRgQ

ALTERNATORS

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

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.

In this video, we can watch the working of electrical motor: https://www.youtube.com/watch?v=DA6FdbpSefU

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.They may also have two or four circuits, in which case they are called two-or four-pole relays.

5)EFFECTS OF ELECTRIC CURRENT

ELECTROMAGNETIC EFFECTS
The electric circuit has created a magnetic field.This effect can be used to produce movement,for example in electric motors, relays and other devices.
The scientist Michael Farady discovered the opposite effect.He noticed that electricity could be generated by using a magnet and an electrical conductor.This principle allows 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.

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 piezoeletric effect, or the ability of some materials to change shape when electricity is applied to them.

5)EFFECTS OF ELECTRIC CURRENT

The movement of electrons though conductive materials produces effects that have useful applications
HEAT
The movement of electrons through an electrical cabe is both slow and disorderly.The electrons often collide, increasing the temperature of the cable itself.
The energy that an electric current produces as heat is called the Joule Effect.It is expressed by the following formula:E=I2*R*T
Most of energy that is consumed by radiators and heaters is converted into heat.

LIGHT
There are various ways that electricity can be used to produce light.We can use 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 fluorescet tube, there is a metallic filament, normally made of tungsteen.There is also an inert gas, such as argon, and a small amount of mercury.When an electric current passes through the filament, electrons are emitted into the inert gas.These react with mercury, creating invisible, ultraviolet light.Then the phosphor coating the tube transforms the ultraviolet light into visible light.
Unfortunately, fluorescent tubes contain a number of toxic substances, such as phosphor and mercury.

LIGHT-EMITTING DIODES(LED)
A light-emitting diode(LED) has layers of semiconductor materials.The n-type layer has extra electrons with negatively charged particles.In contrast, the p-type layer has holes where there aren't enough electrons.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.