How do LEDs (Light Emitting Diodes) work?

 LEDs (Light Emitting Diodes) work by emitting light when an electric current passes through them — a process called electroluminescence.

They’re a special type of diode that not only allows current to flow in one direction but also produces light when doing so.

💡 How LEDs Work — Step by Step

• Material: LEDs are made from a semiconductor material (like gallium arsenide or gallium nitride), with a P-N junction just like a regular diode.
• Forward Bias: When you apply a positive voltage to the anode and negative to the cathode, current flows through the junction.

Electron-Hole Recombination:

• Electrons from the N-type region and holes from the P-type region meet at the junction.
• When they recombine, energy is released as photons — which is visible light (or infrared/UV depending on the material).
• Color of Light: The wavelength (and color) of the light depends on the semiconductor material and its bandgap energy.

🎨 LED Color and Material

• Color Approx. Wavelength Common Material
• Red ~620–750 nm Gallium arsenide (GaAs)
• Green ~495–570 nm Gallium phosphide (GaP)
• Blue ~450–495 nm Gallium nitride (GaN)
• White — Blue LED + phosphor coating

🧠 White LEDs don’t emit white light directly. They use a blue LED coated with a phosphor that glows yellow, and the combination looks white to our eyes.

🔁 Summary of LED Behavior

• LED Condition What Happens
• Forward-biased Current flows → Light is emitted
• Reverse-biased No current flows → No light
• Overvoltage Too much voltage can burn out the LED

⚠️ Important LED Usage Tips

• Current Limiting Resistor: LEDs need one in series to avoid burning out. They typically operate at 2–3.5V and only tolerate 20–30mA.
• Polarity Matters: LEDs are polarized components. You must connect the anode to + and the cathode to –.

🧠 Simple Analogy

• An LED is like a tiny one-way valve that glows when current flows through it in the correct direction — but only glows if you don’t push too hard (too much current).

📦 Common Uses of LEDs

• Flashlights and lamps
• Indicator lights (power ON/OFF)
• Digital displays (clocks, calculators)
• TV and phone screens (LED backlighting)
• Automotive lighting
• Infrared LEDs in remote controls and sensors