Question

If the two ends p and n of a p-n diode junction are joined by a wire , then
A. There will not be a steady current in the circuit.
B. There will not be a steady current from n side to p side.
C. There will be a steady current from p side to n side.
D. There may not be a current depending upon the resistance of the connecting wire.

Answer 1

Hint:-If the two ends p and n of a p-n diode junction are joined by a wire then there will not be a steady current in the circuit. Because both the diffusion current and drift current gets cancelled out to each other.

Complete step-by-step solution:
 If the two ends p and n of a p-n diode junction are joined by a wire then there will be diffusion current p to n side of the diode and there will be another current that is Drift current from n to p side of the diode . If there is no biasing between them then both diffusion current and drift current are equal but they are in opposite to each other hence there will be net current equal to zero.
That means there will not be a steady current in the circuit.
If the two ends p and n of a p-n diode junction are joined by a wire , then There will not be a steady current in the circuit.
Hence option ( A ) is the correct answer .
Some other types of diodes .
Photodiode :- A photodiode is a special purpose p-n junction diode fabricated with a transparent window to allow light to fall on the diode. When light of energy ‘ hv ’ falls on the photodiode more electrons move from valence band to conduction band, due to this, current in the circuit of photodiode in reverse bias increases. As the intensity increases , the current goes on increasing so photodiodes are used to detect light intensity .

Note:- Applications of p-n junction diodes
P-n junction diode ( photo- diode ) is used in video cameras to detect light intensity.
p-n junction diode is used to make (L.E.D) Light Emitting Diode as when a junction diode is forward biased energy is released at junction in the form of photons due to recombination of electrons and holes.
p-n junction diodes are used in diode laser , diode laser is an interesting form of LED in which special construction helps to produce stimulated radiation as in laser.
a p-n junction diode is also used in solar cells and a variable capacitor ( varactor ).