ELECTRICAL QUANTITIES

VOLTAGE OR POTENTIAL DIFFERENCE

In the circuit on the rigth, electrons flow from an electrochemical cell, though a light bulb and the back to the cell.

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

If we want to measure volatage, we can use a voltmeter. This device has two wire that must be connected in parallel to the element athat we are checking.

MEASURING ELECTRIC CURRENT

Electric current (I) is the charge or nmber of electrons that flow throuht the cross-section oof a conductor every second. We can express this mathematically as follows:

                                                    I = Q/t

Electric current is measured in amperes or amps (A) in the International System or SI

ELECTRICAL RESISTANCE: OHM´S LAW

In order to measure the resistance of a lamp, the following experiment was performed with three different circuits

The resistance (R) of a material is equal to the voltage divided by the intensity of the electic current wich travels trough the material. This ratio, wich is called Ohm's Law, can be expressed as follows:
                                                  

                                                                    R=V/I

Ohm's Law has two forms:

                                                       V=RxI     and       I=V/R

The ohm (Ω) is the unit of electric resistance. The following equation can be used

                                              1Ω=1V/1A

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 x I x t

In this SI, this electrical energy is measured joules (J)

Electric power 

The electric power of a load is the amount of energy that it can transform over a certain amount of time.Electric power is measured in watts (W) or kilowatts (kW)

1KW/H= 3600000 j = 3600 kJ