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 sinosoidal current,the average power would be as follows:
Vef= Vmax/√2
4.4.TRANSFORMERS:
Transformers consist of two windings made of cooper wire.If we apply an alternating current to one of them(V1), it will produce a certain voltage in the other (V2) the value will depend on the number of times that the cooper wire has been wrapped around each winding,represented as N1 and N2:
V1/V2=N1/N2.
4.TYPES OF CURRENT
4.1.DIRECT CURRENT:
Between the terminals of a battery,theree is a continuous,stable flow of energy.If we use a voltemeter to measure the current in a car battery,the result will always be 12 volts.This is called direct current.In the same way,if we connect a light bulb to a battery,the electrons always flow in the same direction with the same current.
4.2.ALTERNATING CURRENT:
If we measured the voltaje of an electrical socket,the results could be represented in a graph like the one below:
- The current begins at 0V and increases to 325V.
- The current decreases from 325V to 0V.
- The current becomes negative and decreases to -325V.
- The current increases to 0V.
The variation of any electrical parameter over a period of time is an electric signal.
The tensión or voltage of domestic electricity is an alternating signal becouse it alternates between positive and negative values.Its waveform is also sinusoidal,with a smooth,regular shape.
3.TYPES OF CIRCUITS
3.1.SERIES CIRCUIT:
Two or more elements from 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:
If identical batteries are connected in parallel,the voltaje of a circuit will not increase.However,the total compsumition of energy will be shared between the batteries,so each one will last longer.
3.3.COMBINATION CIRCUIT:
A combination circuit has some elements connected in series and other elements connected in parallel.
- Three loads in a combination circuit.
- Four loads in a combination circuit.
2.3.ELECTRICAL RESISTANCE: Ohm's LAW:
The resistance (R) of a material is equal to the voltaje divided by the intensity of the electric current which travels through the material.This ratio,which is called Ohm's law,can be expresed as follows: R=V/I.
2.4.ELECTRICAL ENERGY AND POWER:
ELECTRICAL ENERGY: If an electric current (I) flows at a particular tension (V) for a certain amount of time (t) ,we can calculate the energy (E) that is consumed: E=V*I*t
In the SI,this electrical energy is measured in joules.(J).
ELECTRIC POWER: If an electric current (I) flows at a particular tension (V),we can calculate the power (P) that is consumed: P=V*I.
If we know the power of a load,we can calculate the electrical energy that it cosumes over a certain amount of time.We simply multiply the power in kilowatts by the amount of time in hours.E=P*T
2.ELECTRICAL QUANTITIES
2.1.VOLTAGE OR POTENTIAL DIFFERENCE:
The amount of energy that of generator (electrochemical cell or battery) can transfer to electrons depends on its voltaje (V) or electric tension.This is measured in volts (V).
2.2.MEASURING ELECTRIC CURRENT:
Electric current (I) is the charge or number of electrons that flow throungh the cross-section of a conductor every second. We can express this methemetically as follows: I = Q/t
Electric current is measured in amperes or amps (A) in the international system or SI.
1.2. DIAGRAMS AND SYMBOLS:
