WORKING, PRINCIPLE & VARIOUS APPLICATIONS OF LED
What Is An LED ?
- LED stands for light emitting diode.
- It is a semiconductor light source.
- Mostly it is used for indication.
- LED have two legs normally known as cathode & anode
Anodeis a + ve terminal ( long leg )
- cathode is a -ve terminal ( small leg )
WORKING OF LED
- We can observe that the N-type silicon is in red color including the electrons which are indicated by the black circles.
- The P-type silicon is in the blue color & it contains holes, they are indicated by the white circles
- The power supply across the p-n junction makes the diode forward biased and pushing the electrons from n-type to p-type.pushing the holes in the opposite direction.
- Electron and holes at the junction are combined.
- The photons are given off as the electrons and holes are recombined.
APPLICATIONS OF LED
- Signal indicators
- umeric and alpha- numeric displays
- Flashlights for portable device
- Torch lights
- Projector light sources
- Traffic lights
- General illumination
- Possible because of white LED development
- Almost all mobile phone color LEDs use white LED backlighting
- Size of displays from smallest to largest
- Mobile phone,PDAs
- Laptop PC monitors
- LCD televisions