Which devices emit light when current passes through them?

Which devices emit light when current passes through them?

• A. Diodes
• B. Capacitors
• C. Transistors
• D. Light-emitting diodes

Answer: (D)

Light-emitting diodes produce light through electroluminescence in a forward-biased semiconductor junction. When current flows, electrons recombine with holes and release energy as photons, giving off light. The color depends on the material’s bandgap. In contrast, a standard diode mainly conducts current without emitting light, a capacitor stores energy, and a transistor amplifies or switches signals. So the component designed to emit light when current passes through it is the light-emitting diode.

Light-emitting diodes produce light through electroluminescence in a forward-biased semiconductor junction. When current flows, electrons recombine with holes and release energy as photons, giving off light. The color depends on the material’s bandgap. In contrast, a standard diode mainly conducts current without emitting light, a capacitor stores energy, and a transistor amplifies or switches signals. So the component designed to emit light when current passes through it is the light-emitting diode.