Tag: junction diode and its voltage current characteristics

Questions Related to junction diode and its voltage current characteristics

For the plate voltage, the plate current in a triode valve is maximum when the potential of :

physics electronic devices introduction to diodes circuit components junction diode and its voltage current characteristics

  1. The gird is positive and plate is negative

  2. The grid is zero and plate is positive

  3. The grid is negative and plate is positive

  4. The grid is positive and plate is positive

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Correct Option: D

For detecting intensity of light we use

physics electronic devices introduction to diodes circuit components junction diode and its voltage current characteristics

  1. Photodiode in forward bias

  2. Photodiode in reverse bias

  3. LED in forward bias

  4. LED in reverse bias

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Correct Option: A

In the forward bias characteristic curve, a diode appears as :

physics electronic devices introduction to diodes circuit components junction diode and its voltage current characteristics

  1. an OFF switch

  2. a high resistance

  3. an ON switch

  4. a capacitor

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Correct Option: C
Explanation:

Diode allows the current to pass through it when it is forward biased.
In the forward biased characteristics curve, a diode appears as an ON switch.

A p-n junction diode cannot be used

physics electronic devices introduction to diodes circuit components junction diode and its voltage current characteristics

  1. as a rectifier.

  2. for converting light energy to electric energy.

  3. for getting light radiation.

  4. for increasing the amplitude of an AC signal.

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Correct Option: D
Explanation:

To increase the amplitude of an AC signal, transistors are used. p-n junction diodes can be used as rectifiers and in photo-diode and LED.

If ‘p’ region of a semi conductor is connected to negative and ‘n’ region to positive pole, it is said to be

physics electric circuits introduction to diodes circuit components junction diode and its voltage current characteristics

  1. directed biased

  2. unbiased

  3. forward biased

  4. reverse biased

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Correct Option: D
Explanation:

In reverse bias, 'p' region of a semi conductor is connected to negative pole and 'n' region to positive pole.

For germanium diode, the junction voltage is about _____.

physics electric circuits introduction to diodes circuit components junction diode and its voltage current characteristics

  1. $0.7V$

  2. $0.3V$

  3. $0.6V$

  4. $3V$

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Correct Option: B
Explanation:

The junction voltage $V _{o}$ for a germanium diode is 0.3 V at room temperature. This potential opposes the diffusion of electrons from n-side and holes from p-side. It is 0.7 eV for Si at room temperature.

Diode can work as

physics electric circuits introduction to diodes circuit components junction diode and its voltage current characteristics

  1. Modulator

  2. Demodulator

  3. Rectifier

  4. Amplifier

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Correct Option: C
Explanation:

Diode can work as rectifier, While converting $AC$ voltage to $DC$ voltage, we use $4$ diodes in the form of wheat stone bridge,It effectively works as rectifier.

Therefore option $C$ is correct

For detecting the light_______________.

physics electric circuits introduction to diodes circuit components junction diode and its voltage current characteristics

  1. The photodiode has to be forward biased

  2. The photodiode has to be reversed biased

  3. The LED has to connected in forward bias mode

  4. The LED has to be connected in reverse bias mode

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Correct Option: B
Explanation:
Photo diode is used to detect light. 
In reverse biased condition, the width of depletion region increases as the the applied reverse bias voltage increases across the diode. So, by applying a larger voltage, more of the incident photons are converted to electric current thereby increasing the efficiency.
In forward biased condition, the width of depletion region decreases so only a small portion of the incident photons get converted to electric current and hence the efficiency is less.
Hence photo diode in reverse biased condition detects light.
Therefore the correct option is (B).

In a diode detector, output circuit consist of $R=1M\Omega \quad and\quad C=1pF$. Calculate the carrier frequency it can detect.

physics electric circuits introduction to diodes circuit components junction diode and its voltage current characteristics

  1. 3000Hz

  2. 1000Hz

  3. 2000Hz

  4. 4000Hz

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Correct Option: B

Select the correct statement from the following 

physics electric circuits introduction to diodes circuit components junction diode and its voltage current characteristics

  1. a diode can be used as a rectifier

  2. a diode cannot be used as a rectifier

  3. the current in a diode is always proportional to the applied voltage

  4. None of these

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Correct Option: A