logo

CuriousTab

CuriousTab

Discussion

Home ‣ Electronics and Communication Engineering ‣ Electronic Devices and Circuits See What Others Are Saying!
  • Question

  • A particular green LED emits light of wavelength 5490, Å, the energy bandgap of the semiconductor material used there is .. h = 6.6 x 10-34 J sec.


  • Options
  • A. 2.26 eV
  • B. 1.98 eV
  • C. 1.17 eV
  • D. 0.74 eV

  • Correct Answer
  • 2.26 eV 

    Explanation
    From Plank equation A particular green LED emits light of wavelength 5490, Å, the energy bandgap of the semiconductor ma joule

    to convert it into electron volt it will be divided by 1.6 x 10-19.

    More questions

    • 1. In pulse width modulation of chopper

    • Options
    • A. T is kept constant and Ton is varied
    • B. Ton is kept constant T is varied
    • C. both T and Ton are varied
    • D. either T or Ton is varied
      • Discuss
    • 2. The colour code on a carbon resistor is green-blue-yellow. The tolerance is

    • Options
    • A. ± 5%
    • B. ± 10%
    • C. ± 20%
    • D. ± 30%
      • Discuss
    • 3. Wave guides are pressurised above normal atmospheric pressure for

    • Options
    • A. increasing the power handling capacity
    • B. improving conductivity of walls
    • C. preventing higher modes from propagation
    • D. varying the wave impedance
      • Discuss
    • 4. A transmission line discontinuity is defined as any interruption in the uniformity of the line.

    • Options
    • A. True
    • B. False
      • Discuss
    • 5. Which of the following is not a valid variable name in C?

    • Options
    • A. 1 a
    • B. a 1 2
    • C. a b 123
    • D. a b c 123
      • Discuss
    • 6. If an amplifier with gain of - 1000 and feedback factor ? = - 0.1 had a gain change of 20% due to temperature, the change in gain of the feedback amplifier would be

    • Options
    • A. 10%
    • B. 5%
    • C. 0.2%
    • D. 0.01%
      • Discuss
    • 7. Permeability is analogous to

    • Options
    • A. resistivity
    • B. retentivity
    • C. conductivity
    • D. coercivity
      • Discuss
    • 8. In a Gunn diode oscillator drift velocity of electron is 107 cm/s and active region length is 10 x 10-4 cm. The natural frequency of oscillation is

    • Options
    • A. 1 MHz
    • B. 10 MHz
    • C. 1 GHz
    • D. 10 GHz
      • Discuss
    • 9. A cycloconverter is a group of controlled rectifiers.

    • Options
    • A. True
    • B. False
      • Discuss
    • 10. If the valence electron is separated from a copper atom, the remaining part of atom has a net charge of

    • Options
    • A. 1
    • B. - 1
    • C. 0
    • D. + 3
      • Discuss

    Comments

    There are no comments.
Enter a new Comment




Aptitude

Engineering

Programming

Reasoning

Links

Copyright ©CuriousTab. All rights reserved.