Tag: special purpose diodes

Questions Related to special purpose diodes

A zener diode can be used as 

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

  1. oscillator .

  2. voltage regulator.

  3. rectifier.

  4. transformer.

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Correct Option: B

At breakdown voltage, the rate of creation of hole-electron pairs is _____  leading to the _______  in current. 

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

  1. increased, decrease

  2. increased, increase

  3. decreased, increase

  4. decreased, decrease

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Correct Option: B
Explanation:

When the reverse voltage across a diode is very large, the valance electrons become free due to applied high electric field and get enough acceleration to make other electrons free, thus create a lot of electron-hole pairs in a short time. As the number of charge carriers increases, current also increases.

Therefore, at breakdown voltage, the rate of creation of hole-electron pairs is increased leading to the increase in current.

Which of these is the best description of a Zener diode ?

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

  1. It is a constant voltage device.

  2. It operates in the reverse region.

  3. It is a constant current device.

  4. It works in forward region.

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Correct Option: A
Explanation:

Zener diode is a p-n junction diode working in the breakdown region. It is used as a voltage regulator/stabilizer to provide a constant voltage from a source whose voltage may fluctuate over a wide range.

Zener-diode is used in.

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

  1. Amplification

  2. Rectification

  3. Oscillator in producing oscillations

  4. Volatge regulation

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Correct Option: D
Explanation:

 A voltage regulator circuit can be designed using a zener diode to maintain a constant DC output voltage across the load in spite of variations in the input voltage or changes in the load current. 

Zener diode is a voltage regulation device.

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

  1. True

  2. False

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Correct Option: A
Explanation:

True. A voltage regulator circuit can be designed using a zener diode to maintain a constant DC output voltage across the load in spite of variations in the input voltage or changes in the load current. 

 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