Tag: special purpose diodes

Questions Related to special purpose diodes

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

Select and write the correct option from the options given in each question:
Optical Detector is:

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

  1. Diode Laser

  2. Laser

  3. LED

  4. Photo Diode

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Correct Option: D

Which of the following is/are true regarding  breakdown voltage of Zener diode?

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

  1. If the reverse bias voltage across a p-n junction diode is increased, at a particular voltage the reverse current suddenly decreases to a large value

  2. The holes in the n-side and the conduction electrons in the p-side are accelerated due to the reverse bias voltage.

  3. The voltage at which the rate of creation of hole-electron pairs is increased leading to the increased current is called avalanche breakdown

  4. None of the above

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Correct Option: B
Explanation:

Consider applying an external voltage to the junction with the the negative terminal connected to the P type material and the positive terminal connected to the N type material. For the P-N junction this would require injecting electrons into the P type material. These electrons would recombine with holes and therefore further deplete the majority charge carriers in the P type semiconductor. 


Also removing electrons from the N type material would obviously cause further depletion the free electrons (the majority charge carriers in the N type semiconductor). This causes a widening of the depletion layer and an increase in the charge at the junction which reinforces the barrier voltage to oppose the applied voltage. The net result is that when the P-N junction is reversed biased it blocks current flow.

Which of the following semi-conducting devices is used as voltage regulator?

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

  1. Zener diode

  2. LASER diode

  3. Photo diode

  4. Solar cell

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Correct Option: A
Explanation:

Zener diode is used as a voltage regulator device because the voltage across the zener diode in reverse bias is constant after reaching certain value i.e. breakdown voltage.

What is true about the breakdown voltage in a zener diode?

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

  1. It decreases when current increases.

  2. It destroys the diode.

  3. It equals the current times the resistance.

  4. It is approximately constant.

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Correct Option: D
Explanation:

As the current in the zener diode increases, the voltage across the diode remains constant. This voltage will be equal to the zener breakdown voltage

When the source voltage increases in a zener regulator, which of these currents remains approximately constant?

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

  1. Series current

  2. Zener current

  3. Load current

  4. Total current

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Correct Option: C
Explanation:

The load current is independent of the source voltage variations and hence remains a constant