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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

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.