6.ELECTROMAGNETIC MECHANISM

6.1 Electromagnetic Generators

Transform mechanical energy into electricity. There are two types of generators, depending on the type of current that is produce. Direct current called dynamos, and produce alternating current are called alternators.

Dynamos:

Consists of a magnet and rotary coil. the coil is located between the two poles of the magnet.
The ends of the coil have two semi.circular conductor, wich form communator.

Alternators:

Is almost identical to a dynamo, exept for the commutator, which consists of two metallic rings connected to carbon brushes. Produce alternating current.

5.1 EFFECTS OF ELECTRIC CURRENT

5.3 Electromagnetic effects.

The scientis Michael Faraday discouvert the opposite effect. He noticed that electricity could be generated by using a magnet and an electrictical conductor this principle allows us to build dynamos and alternators.

5.4 Sound
we can transform the electric current into suond(bells, buzzers). This is based on the piezoelectric effect.

5.EFFECTS OF ELECTRIC CURRENT

5.1 Heat

The energy that an electric current produces as heat is called the Joule Effect. It is expressed by the following formula:  E= I2 x R v t

5.1 Light

There are various ways that electricity can be used to produce ligth.

Incandescent bulbs: When an electric current passes through the metalic filament of a ligth bulb, it produces ligth.

Fluorescent tubes. Inside fluorescent tubes, there is a metallic, normaly made of tungsten.
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 emited into inert gas.
Unfortunated, flourescent tubes contain a numbers of toxic substances, such as phosphor and mercury.

4. TYPES OF CURRENT

4.1 Direct current

Between the terminals of a battery, there is a continous, stable flow of energy. This is called direct current.

4.2 Alternating current

If we measured the voltage of an electrical socket, the results could be represented in a graph like the one below:

The variation of any electrical parameter over a period of time (in this case the electric current) is an electric signal.

The tension or voltage of domestic electricity is an alternating signal because it alternates between positive and negative values. Its waveform is also sinusoidal, with a smooth, regular shape.

4.3 The efficiency of alternating current 

The average power of alternating current is equal to the direct current that is needed to produce the same effect. In the case of an alternating sinusoidal, current, the average power would be as foollows

                                                                       V ef=V max/(Square root) 2

4.4 Transformers

Is a difference between alternating and direct current. Alternating current can be increased or decreased by a transformer.

Transformer consist of two windings made of copper wire. If we apply an .alternating current to one of them, it will produce a certain voltage in the other.

3.TYPES OF CIRCUITS

3.1 Serie circuit

Two or more elements form a series circuit when the output of one element provides the input for the next element.

To calculate the total resistance of a circuit, we add the resistance values of each load:

                                                       R=R1+R2+R3+...

3.2 Parallel circuit

In a parallel circuit, the various components share the same input and output. In other words, the wires from  both sides are joined together.

If identical batteries are connected in parallel, the voltage of the circuit will not increase.

3.3 Combination circuit.

 A combination circuit has some elements conneted in series and other elements connected in parallel.

In this circuit, the current remains constans between elements that are connected in series.

Then we can calculate the current from each power source, and lastly the various voltages.

2. ELECTRICAL QUANTITIES

2.1 Voltage or potencial difference.

The amount of energy that a generator can transfer to electrons depends on its voltage or electric tension. This measured in volts

If we to measure voltage, we can a voltmeter. This device has tow wires that must be connected in parallel to the element that we are cheking

2.2 Measuring electrical current

Electrical current is the charge or number of electrons that flow through the cross-section of a conductor every second. We can express this mathematically as-folows.

we can use an ammeter to measure electric current. This instrument is connected in series, so that all the electrons must pass through it.

2.3 Electrical resistance: ohm's law.

The resistance of a material is equal to the voltage divided by the intensity of the electric current which travels through the materials. This ratio, which is called Ohm's law, can be expressed as follows.

                                                      R=V/I

2.4 Electrial energy and power.

Electrical energy.

If an electric current flows at a particular tension for a certain amount of time, we can calculate the energy that is consumed. E=V x I x t

Electrical power.

If an electric current flows at a particular tension, we can calculate the power that is consumed. 

                                                   P=V x I

we simply multiply the power in kilowatts by the amount of time in hours.

7. ELECTRIC CIRCUITS AND ELECTRONICS

1. An electric circuit

An electric circuit is a pathway for the flow of electrons. It consists of the following parts, which are connected by wires.
Electric current is a continous flow of electrons through a circuit.

1.1 Parts of an electric circuit

Electric circuits consist of varirous parts:

Generators: Is a cells and batteries

Loads: Is a motors, resistor, ligth bulb and bells.

this is a resistor.

Switching devices: Is a switches, push buttons  and 3-way switches.

Is a push buttons.

1.2 Diagrams and symbols. 

We use a system of conventional symbols to simplify the visual representation of electric and electronic circuits, making them easier to understand.