Light Emitting Diode - Meaning, Principle, Uses, Types, FAQs

Light Emitting LED Diode Working

LED Definition and LED meaning: In the semiconductor, electrons recombine with electron holes to produce energy in the form of photons. The energy required for electrons to pass the semiconductor's band gap determines the hue of light (equivalent to the energy of photons). The white light can be produced by several semiconductors, or by the luminous phosphorus coating, on the semiconductor device.

JEE Main 2025: Physics Formula | Study Materials | High Scoring Topics | Preparation Guide

JEE Main 2025: Syllabus | Sample Papers | Mock Tests | PYQs | Study Plan 100 Days

NEET 2025: Syllabus | High Scoring Topics | PYQs

This Story also Contains

1. Light Emitting LED Diode Working
2. What is LED light emitting LED diodes working?
3. Working of LED and Principle of LED
4. Uses of LED
5. Types of LED Light emitting LED diode working

The first LED, which appeared as functional electrical components in 1962, emitted low-intensity infrared (IR) light. Remote-control circuits, such as those found in a wide range of consumer gadgets, utilise infrared LED. The original visible-light LED had a low intensity and were only available in red. Modern LED come in visible, ultraviolet (UV), and infrared wavelengths and can produce high, low, or intermediate light output.

Early LED were commonly employed as indicator lamps and in seven-segment displays, replacing small incandescent bulbs. Recent technological advances have resulted in high-output white light LED that can be utilised to illuminate interiors and outdoor spaces. LED have spawned a slew of novel displays and sensors, and their rapid switching rates are important in sophisticated communications.

Also read -

• NCERT Solutions for Class 11 Physics
• NCERT Solutions for Class 12 Physics
• NCERT Solutions for All Subjects

What is LED light emitting LED diodes working?

LED stands for Light Emitting Diode and it is a device which emits light by flowing a current to the positive-negative junction like a semiconductor laser. It emits various wavelength lights in the ultraviolet, visible and infrared regions, corresponding to its band gap energy.

Circuit of a Light emitting LED diode working

Simple LED circuit with current limiting resistor

LED symbol and LED diagram (LED circuit diagram)

In circumstances where traditional circuits, such as a standard diode are employed, the LED also have a specified voltage drop forward. The voltage drop is determined by the LED's current, the colour of the light generated and other factors. The voltage drop varies between 1.5V and 2.5V for currents ranging from 10 to 50 mA.

Also read :

• NCERT notes Class 12 Physics Chapter 14 Semiconductor Electronics: Materials, Devices and Simple Circuits
• NCERT solutions for Class 12 Physics Chapter 14 Semiconductor Electronics: Materials, Devices and Simple Circuits
• NCERT Exemplar Class 12 Physics Solutions Chapter 14 Semiconductor Electronics Materials, Devices and Simple Circuits

Working of LED and Principle of LED

The LED is connected in the forward bias, which allows the current to flow in the forward direction. The flow of current is because of the movement of electrons in the opposite direction. The recombination shows that the electrons move from the conduction band to the valence band and they emit electromagnetic energy in the form of photons. The energy of photons is equal to the gap between the valence and the conduction band.

The energy is released in the form of heat in conventional LED diode workings. However, with an LED, the release of energy in the form of photons would result in the emission of light energy. The process is referred to as electroluminescence.

How much energy is discharged in the form of light in LED is determined by the forbidden energy gap. As a result, the light colour and visibility cannot be altered based on its wavelength. By doping the light with various contaminants, the colour and wavelength of the light emitted may be determined.

Uses of LED

LED are used in a variety of industries, such as optical communication, alarm and security systems, remote-controlled operations, robotics, and so on. Because of its long-lasting capability, low power needs, quick response time, and fast switching capabilities, it is uses of LED in a variety of applications. The following are some of the standards that LED adheres to:

1. Backlighting for televisions
2. Frequently seen in exhibits
3. Applied to automobiles
4. LED are utilised in light dimming.

NCERT Physics Notes:

• NCERT Notes Class 11th Physics
• NCERT Notes Class 12th Physics
• NCERT Notes For All Subjects

Types of LED Light emitting LED diode working

1. Gallium Arsenide (GaAs) is an infrared semiconductor.
2. Red to infrared, orange Gallium Arsenide Phosphide (GaAsP).
3. High-brightness red, orange-red, orange, and yellow Aluminium Gallium Arsenide Phosphide (AlGaAsP).
4. Gallium Phosphide (GaP) comes in three colours: red, yellow, and green.
5. Green Aluminium Gallium Phosphide (AlGaP).
6. Green, emerald green gallium nitride (GaN).
7. Near-ultraviolet gallium indium nitride (GaInN) — bluish-green and blue.
8. As a substrate, Silicon Carbide (SiC) is blue.
9. Blue Zinc Selenide (ZnSe).
10. AlGaN (Aluminium Gallium Nitride) – ultraviolet.

LED have a wide range of shapes and sizes and colours. The colour of the plastic lens is frequently, but not always, the same as the colour of the light emitted. Infrared LED, for example, are frequently made of purple plastic, whereas most blue gadgets have colourless housings.

LED construction

Also check-

• NCERT Exemplar Class 11th Physics Solutions
• NCERT Exemplar Class 12th Physics Solutions
• NCERT Exemplar Solutions for All Subjects