Light emitting diode

1. Welcome
To our
Presentation

2. Submitted to:
Md. Sayeedur Rahman
Lecturer in physics
Submitted by :
171-23-4940
171-23-5013
171-23-4998
171-23-4984
171-23-5019
Section: C
Dept. of TE

3. Presentation Topic

4. • 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.

5. LED: How It Works
 When current flows across a diode
negative electrons move one way and
positive holes move the other way.
 Therefore when a free electron falls it
losses energy, the wholes exist at a
lower energy level than the free
electrons
 This energy is emitted in a form of a
photon, which causes light.
 The color of the light is determined by
the fall of the electron and hence energy
level of the photon

6. Inside a Light Emitting Diode
1. Transparent
Plastic Case
2. Terminal Pins
3. Diode

7. Some Types of LED
Bar graph 7-segment Starburst Dot matrix
•There are some different types of LED.
As for example we can see below:

8. Applications
• Sensor Uses
• Mobile Uses
• Sign Uses
• Automative Uses
• Light Uses
• Decoration Uses
• Laptop & Smart TV Uses

9. Uses inUses in SensorSensor
•LED are used for scanning barcode or QR code

10. Uses in Mobile
•LED are used smartphones for mobiles display

11. •LED is used as Road signals & Cross- Signals

12. •LED is used in automobiles headlight & back-
light

13. •LED is used in light bulbs,
which gives very high
quality light

14. •LED is used for latest technological Smart TV
and laptops.

15. •LED is used for different
types of home or outside
decorations.

16. •LED is used in
multimedia
projector.