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  • Question

  • Assertion (A): Impatt diode is an avalanche diode.

    Reason (R): Avalanche breakdown phenomenon occurs when a p-n junction is reverse biased.


  • Options
  • A. Both A and R are correct and R is correct explanation of A
  • B. Both A and R are correct but R is not correct explanation of A
  • C. A is correct but R is wrong
  • D. A is wrong but R is correct

  • Correct Answer
  • Both A and R are correct but R is not correct explanation of A 

    Explanation
    An Impatt diode has n+ - p - i - p + structure and is used with reverse bias.

    It exhibits negative resistance and operates on the principle of avalanche breakdown.

    Impatt diode circuits are classified as broadly tunable circuit, low Q circuit and high Q circuit.

    The impedance of Impatt diode is a few ohms. The word Impatt stands for Impact Avalanche Transit Time diode.

    The features of Impatt diode oscillator are : frequency 1 to 300 GHz, Power output (0.5 W to 5 W for single diode circuit and upto 40 W for combination of several diodes), efficiency about 20%.

    Its applications include police radar systems, low power microwave transmitter etc.

    More questions

    • 1. A lag compensator is essentially a

    • Options
    • A. low pass filter
    • B. high pass filter
    • C. band pass filter
    • D. either (a) or (b)
      • Discuss
    • 2. If q is charge on an electron, R is radius of electron orbit and ? is angular velocity of electron rotation, the magnetic dipole moment of electron in orbit is

    • Options
    • A. 0.5 q?R
    • B. 0.5 q2?2R2
    • C. 0.5 q?R2
    • D. 0.5 q?2R
      • Discuss
    • 3. For a photoconductor with equal electron and hole mobilities and perfect ohmic contacts at the ends, an increase in intensity of optical illumination results in

    • Options
    • A. a change in o.c voltage
    • B. a change in s.c current
    • C. decrease in resistance
    • D. increase in resistance
      • Discuss
    • 4. The temperature below which certain materials are antiferromagnetic and above which they are paramagnetic is called

    • Options
    • A. Weiss temperature
    • B. Curie temperature
    • C. Neel temperature
    • D. None of the above
      • Discuss
    • 5. The colour code on a carbon resistor is yellow-violet-orange. The value of resistance is

    • Options
    • A. 17000 ?
    • B. 27000 ?
    • C. 37000 ?
    • D. 47000 ?
      • Discuss
    • 6. The dielectric constant of ferroelectric materials can be expressed by the equation

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 7. Assertion (A): The optical dielectric constant (i.e., ?r at optical frequencies)of ionic dielectrics is less than static dielectric constant.

      Reason (R): At optical frequencies, Pi = 0.


    • Options
    • A. Both A and R are true and R is correct explanation of A
    • B. Both A and R are true but R is not correct explanation of A
    • C. A is true but R is false
    • D. A is false but R is true
      • Discuss
    • 8. Assertion (A): The gate current of an SCR is always in the form of pulses.

      Reason (R): The gate losses, in pulse triggering, are low.


    • Options
    • A. Both A and R are correct and R is correct explanation of A
    • B. Both A and R correct but R is not correct explanation of A
    • C. A is correct but R is wrong
    • D. A is wrong but R is correct
      • Discuss
    • 9. A conductor carries 10 A current in + x direction and is lying in a field having a flux density 0.2 T directed along + z direction. The magnitude of force per metre length and direction are

    • Options
    • A. 2 N, + y direction
    • B. 2 N, - y direction
    • C. 0.02 N, + y direction
    • D. 0.02 N, - y direction
      • Discuss
    • 10. If ?0 is the angular frequency of rotation of electron in the absence of magnetic field, the angular frequency ?, when a magnetic field B is acting is ? ? ?0 + (e/2m)B.

    • Options
    • A. True
    • B. False
      • Discuss

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