Engineering Theory & Mathematical Model
Shorter-wavelength blue photons (~465 nm) carry higher quantum energy (~2.67 eV) than longer-wavelength red photons (~630 nm, ~1.97 eV). Consequently, wide-bandgap InGaN blue and white LEDs exhibit a higher forward voltage drop (~3.05V) than red LEDs (~1.85V), leaving less voltage across identical ballast resistors.
Interactive Lab Procedure
- Hover over each LED (Red, Green, Blue) to compare their distinct forward voltages ΔV and branch currents.
- Sweep supply V1 slowly down from 5.0V toward 2.0V: watch the Blue LED extinguish first while Red stays lit!
- Observe CH1 (Red Vf) vs CH2 (Blue Vf) directly on the oscilloscope.
Technical FAQ
What is the core governing formula for Red, Green & Blue LED Semiconductor Bandgap Voltage Simulator?
Vf ≈ Eg / q = h × c / (q × λ) — Shorter-wavelength blue photons (~465 nm) carry higher quantum energy (~2.67 eV) than longer-wavelength red photons (~630 nm, ~1.97 eV). Consequently, wide-bandgap InGaN blue and white LEDs exhibit a higher forward voltage drop (~3.05V) than red LEDs (~1.85V), leaving less voltage across identical ballast resistors.
Can I modify component values and rewire this circuit live?
Yes! The schematic above runs a live MNA SPICE engine. Click any part to adjust parameters, add or delete wires and components, and click Share URL to save your custom topology.