28-06-2012, 01:34 PM
LIGHT EMITTING DIODES:-
LIGHT EMITTING DIODES.docx (Size: 1.02 MB / Downloads: 36)
A light emitting diode (LED) is essentially a PN junction opto-semiconductor that emits a monochromatic (single color) light when operated in a forward biased direction.
LEDs convert electrical energy into light energy. They are frequently used as "pilot" lights in electronic appliances to indicate whether the circuit is closed or not.
How Does A LED Work? (1/2):-
When sufficient voltage is applied to the chip across the leads of the LED, electrons can move easily in only one direction across the junction between the p and n regions.
In the p region there are many more positive than negative charges.
When a voltage is applied and the current starts to flow, electrons in the n region have sufficient energy to move across the junction into the p region.
How Much Energy Does an LED Emit?:-
The energy (E) of the light emitted by an LED is related to the electric charge (q) of an electron and the voltage (V) required to light the LED by the expression: E = qV Joules.
This expression simply says that the voltage is proportional to the electric energy, and is a general statement which applies to any circuit, as well as to LED's. The constant q is the electric charge of a single electron, -1.6 x 10-19 Coulomb.
Applications:-
Sensor Applications
Mobile Applications
Sign Applications
Automative Uses
LIGHT EMITTING DIODES.docx (Size: 1.02 MB / Downloads: 36)
A light emitting diode (LED) is essentially a PN junction opto-semiconductor that emits a monochromatic (single color) light when operated in a forward biased direction.
LEDs convert electrical energy into light energy. They are frequently used as "pilot" lights in electronic appliances to indicate whether the circuit is closed or not.
How Does A LED Work? (1/2):-
When sufficient voltage is applied to the chip across the leads of the LED, electrons can move easily in only one direction across the junction between the p and n regions.
In the p region there are many more positive than negative charges.
When a voltage is applied and the current starts to flow, electrons in the n region have sufficient energy to move across the junction into the p region.
How Much Energy Does an LED Emit?:-
The energy (E) of the light emitted by an LED is related to the electric charge (q) of an electron and the voltage (V) required to light the LED by the expression: E = qV Joules.
This expression simply says that the voltage is proportional to the electric energy, and is a general statement which applies to any circuit, as well as to LED's. The constant q is the electric charge of a single electron, -1.6 x 10-19 Coulomb.
Applications:-
Sensor Applications
Mobile Applications
Sign Applications
Automative Uses