MCQs on Analog Electronics


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01․ The leakage current in a pn junction is in order of
A
KA
µA
None of the above

Leakage current flows due to minority carrier in pn junction. So its value is very small in the order of µA.

02․ A pn junction/Diode is a/an
Bidirectional component
Unidirectional Component
Linear component
None of the Above

A pn junction / Diode is an unidirectional component. It can conduct only when it is forward biased and act as a close switch, in reverse bias condition it act as a open switch. Forward bias means anode voltage is greater than the cathode voltage.

03․ A semiconductor material is formed by
Covalent bonds
Metallic bonds
Electrovalent bonds
None of the above

Semiconductor material are formed by Covalent bonds. It is formed by sharing of four electrons by two atoms, each electron are sharing four other electrons from other atom.

04․ The forbidden energy gap between valance band and conduction band in semiconductor material is about
1eV
15 eV
0 eV
None of the above

The forbidden energy gap between valance band and conduction band in a semiconductor devices is arround 1ev whereas in insulator it is 15 ev and in conductor it is 0 ev.

05․ N-type extrinsic semiconductor is obtained by adding
trivalent impurity
pentavalent impurity
tetravalent impurity
all of the above

N-type extrinsic semiconductor is obtained by adding pentavalent impurity. Pentavalent impurity has one more extra electron after covalent bond. So pentavalent impurity gives number of free electrons and n type material are obtained.

06․ When Semiconductor materials is heated its resistance
increases
decreases
remains constant
none of the above

When semiconductor material is heated, electron break away from the atoms and move free from the valance band to the conduction band. So, its conductivity increases and resistivity decreases. As a result resistance decreases.

07․ Which of the following is Pentavalent impurity?
boron
antimony
indium
gallium

Pentavalent impurity has 5 electrons in valance shell and antimony also have 5 electrons in outer most orbit. So, antimony is a pentavalent impurity. Boron, indium and gallium are trivalent impurity.

08․ The amount of time between the creation and disappearance of a free electrons is called
recombination
bound electrons
drift velocity
life time of the carriers

The amount of time between the creation and disappearance of a free electrons is called life time of the carriers. Life time of the carriers varies from nano-second to several microseconds depending on perfect the crystal is and many other factors.

09․ The majority carrier in P-type extrinsic semiconductor material is
Holes
Electrons
Both Holes and Electrons
None of the above

The P-type semiconductor material is obtained by adding trivalent impurity. Trivalent impurity has deficiency of one electron when forming a covalent bond and it creates holes. Trivalent impurity make available positive carriers because they create holes which can accept electrons and thus it the majority carriers are holes.

10․ Conduction electrons have more mobility than holes because they
have negative charge
are free
need less energy to move them
none of the above

The mobility of electrons is more than that of holes because the probability of an electron having the energy required to move to an empty state in the conduction band is much greater than the probability of an electron having the energy required to move to the empty state in valance band. The mobility of hole is about half that of electrons.

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