Tag: electronic devices

Questions Related to electronic devices

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

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

  1. Decreases

  2. Stays the same

  3. Increases

  4. Equals the voltage divided by the resistance

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Correct Option: C
Explanation:

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

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

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

  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

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Correct Option: B
Explanation:

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

The load voltage is approximately constant when a zener diode is

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

  1. Forward-biased

  2. Reverse-biased

  3. Operating in the breakdown region

  4. Unbiased

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Correct Option: C
Explanation:

The zener voltage will be a constant only when it is operating in the breakdown region

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? 

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

  1. $40 \ mA$

  2. $60 \ mA$

  3. $50 \ mA$

  4. $45 \ mA$

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Correct Option: B

In a zener regulated power supply of a zener diode with $V _z$ = 6V is used for regulation. The load current is to be 4 mA and the unregulated input is 10 V. The value of series resistor $R _s$ is

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

  1. less than $ 5 \ \Omega$

  2. Infinite

  3. greater than 100 $\Omega$

  4. zero

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Correct Option: C

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

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

  1. increase

  2. decrease

  3. remain constant

  4. first increase then decrease

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Correct Option: A

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

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

  1. Impact ionisation

  2. Internal field emission

  3. High doping concentration

  4. All of these

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Correct Option: D

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 

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

  1. 2 C and 2 V

  2. C/2 and V/2

  3. 2 C and V/2

  4. C/2 and 2 V.

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Correct Option: D
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.

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

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

  1. ampere

  2. milli-ampere

  3. it depends on the applied voltage

  4. micro-ampere

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Correct Option: C

The number of minority carriers crossing the junction of a diode depends primarily on the :

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

  1. concentration of doping impurities

  2. magnitude of potential barrier

  3. magnitude of the forward bias voltage

  4. rate of thermal generation of electron-hole pair

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Correct Option: C