Target Exam

CUET

Subject

Physics

Chapter

Semiconductors and Electronic Devices

Question:

LED's have following advantages over incandescent low power lamps.

A. Low operational voltage and less power.
B. No warm up time required.
C. LED must at least have a band gap of 1.8 eV.
D. $GaAs_{1-x} P_x$ is used for making LED's of different colours
E. The band width of emitted light in LED's is 100 Å to 500 Å

Choose the correct answer from the options given below:

Options:

A, B, D only

C, D, E only

All correct

A, B, C only

Correct Answer:

All correct

Explanation:

The correct answer is Option (3) → All correct

  • LED's operate at low voltages and there by consume significantly less power.
  • Unlike incandescent lamps, LED's reach full brightness immediately, without any warm-up period.
  • A band gap of around 1.8 eV is typically necessary for efficient light emission in LED's.
  • The emitted light from LED's has a relatively narrow bandwidth, usually in a range of 100°A - 500°A.
  • Gallium arsenide phosphide is commonly used to produce LED's of various colours.