5)EFFECTS OF ELECTRIC CURRENT

The movement of electrons though conductive materials produces effects that have useful applications
HEAT
The movement of electrons through an electrical cabe is both slow and disorderly.The electrons often collide, increasing the temperature of the cable itself.
The energy that an electric current produces as heat is called the Joule Effect.It is expressed by the following formula:E=I2*R*T
Most of energy that is consumed by radiators and heaters is converted into heat.

LIGHT
There are various ways that electricity can be used to produce light.We can use an electronic device called a light-emitting diode(LED)
INCANDESCENT BULBS
When an electric current passes through the metallic filament of a light bulb, it produces light. This phenomenon is called incandescence.

FLUORESCENT TUBES
Inside a fluorescet tube, there is a metallic filament, normally made of tungsteen.There is also an inert gas, such as argon, and a small amount of mercury.When an electric current passes through the filament, electrons are emitted into the inert gas.These react with mercury, creating invisible, ultraviolet light.Then the phosphor coating the tube transforms the ultraviolet light into visible light.
Unfortunately, fluorescent tubes contain a number of toxic substances, such as phosphor and mercury.

LIGHT-EMITTING DIODES(LED)
A light-emitting diode(LED) has layers of semiconductor materials.The n-type layer has extra electrons with negatively charged particles.In contrast, the p-type layer has holes where there aren't enough electrons.When electricity is applied to the LED,the electrons and holes cross over into the active layer, where they combine and produce photons, or particles of light.