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