5. EFFECTS OF ELECTRIC CURRENT ( 5.1 + 5.2)

The movement of electrons trhough conductive  materials produces effects that have useful applicattions.

5.1. Heat

The energy that an electric current produces as heat is called the Joule Effect. 
It is expressed by the following formula:

E = I^2 x R x t

5.2.  Light

There are various ways that electricity can be used to produce light:

Incandescent bulbs

When an electric current passes trough the metalic filament of a light bulb, it produces light. This is called incandescense.

Fluorescents tubes

Inside a fluoreescent tube, there is a metallic filament, normally, made of tungsten. When an electric current passes trough the filament, electrons are emitted into the inert gas. These react with mercury, creating invisible, ultraviolet light. Then the phosphor coating inside the tube transforms the ultraviolet light into visible light.

Light-emitting diodes (LED)

A LED has layers of semiconductors materials. When the electricity is applied to it, the electrons and holes cross over into the active layer, where they combine and produce photons or particles of light.