Question

A light emitting diode (LED) is fabricated using GaAs semiconducting material whose band gap is 1.42 eV. The wavelength of light emitted from the LED is:

• A. 650 nm
• B. 1243 nm
• C. 875 nm
• D. 1400 nm

Answer 1

The Correct Option is C

The wavelength of light emitted from an LED is related to its energy gap by the formula:

\( \lambda = \frac{1240}{E_g} \),

where:

• \( \lambda \) is the wavelength in nanometers (nm),
• \( E_g \) is the energy gap in electron volts (eV).

Substitute \( E_g = 1.42 \, \text{eV} \):

\( \lambda = \frac{1240}{1.42} \).

Perform the calculation: \( \lambda = 875 \, \text{nm} \, \text{(approximately)}. \)
Final Answer: 875 nm.