Theory of electricity



Molecule:  The molecule is the smallest possible part of a physical element , Example : a molecule of water ( H2O ) is always water .


Atom:  The atom is an element of the molecule ( it is no longer a physical element ) .  Example : two atoms of hydrogen and one of oxygen give a molecule of water .


The atom is constituted by a nucleus around of which turn electrons .  In elements like copper wires the electrons can leave atoms .


Electricity:  If we connect something between the poles of a current’s generator we create an electric circuit  , electrons form a current that circulates from a pole to the other .



The electric current that circulates from the battery has three effects : it lights the bulb ,


it provokes the electrolysis of the water and it deviate the needle of the compass .


The electric current has a thermal effect , a chemical effect and a magnetic effect


 ( a magnetic field can create the movement of an engine ) .


We can compare an electric current to a liquid that circulates in pipes ,


 An example is a central heating .


The battery would correspond to the boiler and the bulb to a radiator .




We can generate an electric current by the chemistry ( battery, accumulator ) or by the magnetism ( dynamo, alternator ) .


The magnetic effect is reversible :  a loud speaker produces a sound but it can also serve as microphone ( in an intercom ) .


The current can be direct ,  it circulates then in one way ( battery , accumulator ) , or it is alternative :  it circulates once in a way


then in the other ( line, sounding signal ) .


The voltage of the line ( in France ) is 220 volts with a frequency ( curve of sinus ) of 50 Hertz ( 50 go and return by second ) .


We consider since the discovery of electricity that the current circulates between the pole + to the pole - .  In reality this is the contrary because electrons are negative ( - ) .


Anecdote :  If we drive in a potato a stem of copper and a stem of zinc we obtain a battery :  the potato’s battery  ( not very powerful ) .