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
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 ) .