Tag: junction diode and its voltage current characteristics

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Questions Related to junction diode and its voltage current characteristics

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

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

  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
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In a triode, the plate current is controlled by the grid potential. When both the grid and the plate are positive, they both attract electrons emitted from the cathode, maximizing the plate current.

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

For detecting intensity of light we use

  1. Photodiode in forward bias

  2. Photodiode in reverse bias

  3. LED in forward bias

  4. LED in reverse bias
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Photodiodes are semiconductor light sensors designed to operate in reverse bias. In reverse bias, the width of the depletion region increases, and the reverse saturation current varies linearly with the intensity of incident light, making it sensitive and fast for detection.

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

A p-n junction diode cannot be used

  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.
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

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

  1. directed biased

  2. unbiased

  3. forward biased

  4. reverse biased
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

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

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

For germanium diode, the junction voltage is about _____.

  1. $0.7V$
  2. $0.3V$
  3. $0.6V$
  4. $3V$
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

For detecting the light_______________.

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
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).
Multiple choice physics electric circuits introduction to diodes circuit components junction diode and its voltage current characteristics

Select the correct statement from the following 

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A diode allows current to flow in only one direction, which is the fundamental principle behind rectification, converting AC to DC.