Light Emitting Diode (L.E.D) is a diode, why L.E.D could emits light where a normal diode couldn't?

Answer 1

Electrons lose energy when they move down the potential drop (0.7 volts in Si) in a foward biased diode. They lose it as heat normally. This is conducted away by the case or wires and radiated weakly in the InfraRed.

In LED's they lose the energy strongly in the InfraRed, visible or now UV. Some Lase..

When the forward bias voltage is large enough 2,3volts then the radiation is in the visible spectrum and we see the light.
(Look up the energy in eV of say yellow light photons and check it out!)
But this is only possible if the diode is constructed to transmit the light,if the material it is made from is transparent, and the energy loss is not in lots of small steps

Answer 2

In electronics, a diode is a component that restricts the direction of movement of charge carriers. Essentially, it allows an electric current to flow in one direction, but blocks it in the opposite direction. Thus, the diode can be thought of as an electronic version of a check valve. Circuits that require current flow in only one direction will typically include one or more diodes in the circuit design.

Early diodes included "cat's whisker" crystals and vacuum tube devices (called thermionic valves in British English Dialect). Today the most common diodes are made from semiconductor materials such as silicon or germanium.

An LED is a diode but is made specifically to produce light. A normal diode does not need to do this. The primary function of a diode is not emitting light.

I hope this answers the question somewhat, it was hard to understand exactly what you want to know.

Answer 3

'cuz in LED electrons of the same charge are accumulated in separate from opposite charges so they have stronger energy to make the move across the region in between by the law of attraction when voltage is applied and current start to flow that result in converting the potential energy to electromagnetic energy in the form of photon or particles of light.