Compound semiconductors

Why is LED lighting more energy-efficient than incandescent bulbs?

  1. ABecause it lights by heating a filament to a high temperature
  2. BBecause LEDs emit no light at all, only heat
  3. CBecause it converts electrical energy directly into light inside the semiconductor, losing a smaller share as heat
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Answer: C. Because it converts electrical energy directly into light inside the semiconductor, losing a smaller share as heat

Incandescent bulbs light by heating a filament, so most of the input power becomes infrared (heat). LEDs convert electricity directly into light through electron-hole recombination, so they need far less power for the same brightness.

  • A. Heating a filament is how incandescent bulbs work.
  • B. LEDs are devices that emit light.
  • C. Correct. Converting electricity directly into light makes them efficient.
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More Compound semiconductors questions

  1. Which compound semiconductor, with very high electron mobility, is used in magnetic sensors (Hall elements) and the like?
  2. What is the gate structure of the MESFET, long used as a high-frequency GaAs transistor?
  3. Which material, named for its crystal structure, has attracted intense research as a high-efficiency solar cell material that can be made by low-temperature processes such as coating?
  4. In LEDs with an InGaN emitting layer, how does the emission color change when the indium (In) fraction is increased?
  5. What material is used for the blue-violet semiconductor laser of about 405 nm that reads and writes Blu-ray discs?