Tag: electronic devices

Quizzes (9) Questions (113)

Questions Related to electronic devices

Multiple choice zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

 If the series resistance decreases in an unloaded zener regulator, the zener current

  1. Decreases

  2. Stays the same

  3. Increases

  4. Equals the voltage divided by the resistance
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

current increases as the resistance decreases, as zener current is inversely proportional to the series resistance

Multiple choice zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

Zener diodes with breakdown voltage ranging over 2V- 200 V are commercially available. Breakdown voltage of a zener diode

  1. Increases with increasing doping concentration

  2. Decreases with increasing doping concentration

  3. Does not depend on doping concentration

  4. May increases or decreases with increasing doping concentration
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For Zener Diodes, the breakdown voltage decreases with increasing doping concentration.

Multiple choice zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

A zener diode is specified as having a breakdown voltage of $9.1 V$, with a maximum power dissipation of $364 \ mW$. What is the maximum current the diode can handle? 

  1. $40 \ mA$
  2. $60 \ mA$
  3. $50 \ mA$
  4. $45 \ mA$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Maximum power dissipation is the product of breakdown voltage and maximum current. Dividing the maximum power by the Zener voltage yields I_max = P / V_z = 364 mW / 9.1 V = 40 mA. Thus, option A is the correct choice.

Multiple choice zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

If the revers bias voltage applied  to a p-n junction diode is increased, its barrier capacitance would:

  1. increase

  2. decrease

  3. remain constant

  4. first increase then decrease
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Barrier capacitance, also known as transition or depletion capacitance, is inversely proportional to the width of the depletion region. Increasing the reverse bias voltage widens the depletion layer, which in turn decreases the barrier capacitance. Therefore, option B is correct.

Multiple choice zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

In a zener diode, break down occurs in reverse bias due to

  1. Impact ionisation

  2. Internal field emission

  3. High doping concentration

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Zener breakdown occurs due to high electric fields (internal field emission) in heavily doped diodes, while avalanche breakdown occurs due to impact ionization. Both are mechanisms associated with reverse bias breakdown.

Multiple choice zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

Two capacitors each having capacitance C and breakdown voltage V are joined in series. The capacitance and the breakdown voltage of the combination will be 

  1. 2 C and 2 V

  2. C/2 and V/2

  3. 2 C and V/2

  4. C/2 and 2 V.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

We know that the charge on a capacitor is 
$\begin{array}{l} Q=CV \\ C\propto \dfrac { 1 }{ V }  \\ in\, \, series\, \, combination \\ { C _{ net } }=\dfrac { { { C _{ 1 } }{ C _{ 2 } } } }{ { { C _{ 1 } }+{ C _{ 2 } } } }  \\ Hence, \\ { C _{ eq } }=\dfrac { C }{ 2 }  \\ { V _{ combination } }=2V \end{array}$

$\therefore$ option $D$ is correct.
Multiple choice zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

What is the order of the reverse saturation current before breakdown in a Zener diode

  1. ampere

  2. milli-ampere

  3. it depends on the applied voltage

  4. micro-ampere
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Before the breakdown voltage is reached, a Zener diode acts like a normal diode under reverse bias, where only minority carriers contribute to a very small leakage current. This reverse saturation current is typically on the order of microamperes, making option D correct.