If a Small Voltage is Applied to a P-n Junction Diode, How Will the Barrier Potential Be Affected When It is Forward Biased - Physics


If a small voltage is applied to a p-n junction diode, how will the barrier potential be affected when it is (i) forward biased



If a small voltage is applied to a p–n junction diode in the forward bias, then the barrier potential decreases.

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2014-2015 (March) Panchkula Set 3


With the help of a neat circuit diagram, explain the working of a photodiode. 

Colour of light emitted by LED depends upon__________________ .

  1. its forward bias
  2. its reverse bias
  3. the band gap of the material of semiconductor
  4. its size

How is a Zener diode fabricated?

The width of depletion region of p-n junction diode is _______.

(A) 0.5 nm to 1 nm

(B) 5 nm to 10 nm

(C) 50 nm to 500 nm

(D) 500 nm to 1000 nm


State its any ‘two’ uses of photodiode.

Write briefly the important processes that occur during the formation of p−n junction. With the help of necessary diagrams, explain the term 'barrier potential'.

Describe briefly, with the help of a diagram, the role of the two important processes involved in the formation of a p-n junction ?

Explain the formation of depletion layer and potential barrier in a p−n junction.

An ideal diode should pass a current freely in one direction and should stop it completely in the opposite direction. Which is closer to ideal-vacuum diode or a p-njunction diode?

The plate resistance of a triode is 8 kΩ and the transconductance is 2.5 millimho. (a) If the plate voltage is increased by 48 V and the grid voltage is kept constant, what will be the increase in the plate current? (b) With plate voltage kept constant at this increased value, by how much should the grid voltage be decreased in order to bring the plate current back to its initial value?

Write the important considerations which are to be taken into account while fabricating a p-n junction diode to be used as a Light Emitting Diode (LED). What should be the order of band gap of an LED,  if it is required to emit light in the visible range? Draw a circuit diagram and explain its action. 

Answer the following question.
Draw solar cell V-I characteristics.

With reference to Semiconductor Physics,

Name the process that causes depletion region in a p-n junction.

Explain photodiode.

What is the magnitude of the potential barrier across a Ge p-n junction?

Name the device which converts the change in intensity of illumination to change in electric current flowing through it. Plot I-V characteristics of this device for different intensities. State any two applications of this device.

Pressure P varies as P = `alpha/beta "exp" (- (alpha x)/"k"_"BT")`, where x denotes the distance, kB is the Boltzmann's constant, T is the absolute temperature and α and β are constant. The dimension of β is ______.

A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. lt can detect a signal of wavelength ______.

For LED's to emit light in visible region of electromagnetic light, it should have energy band gap in the range of:

Which one of the following is not the advantage of LED?

Consider the following statements (A) and (B) and identify the correct answer.

  1. A Zener diode is connected in reverse bias when used as a voltage regulator.
  2. The potential barrier of the p-n junction lies between 0.1 V to 0.3 V.

In Figure, assuming the diodes to be ideal ______.

The amplifiers X, Y and Z are connected in series. If the voltage gains of X, Y and Z are 10, 20 and 30, respectively and the input signal is 1 mV peak value, then what is the output signal voltage (peak value)

  1. if dc supply voltage is 10V?
  2. if dc supply voltage is 5V?

If the resistance R1 is increased (Figure), how will the readings of the ammeter and voltmeter change?

Draw solar cells of I-V characteristics.

The value of power dissipated across the Zener diode (Vz = 15 V) connected in the circuit as shown in the figure is x × 10–1 watt. The value of x, to the nearest integer, is ______.


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