Mcqs of PN junction | Semiconductor Whatswho.com

Mcqs of pn junction, silicon, and energy levels of the 4th chapter which is most important. Usually, these type of Mcqs of pn junction comes in job tests not all of them but 2 or 3 from this post. these Mcqs of pn junction are prepared for the job seekers.

A semiconductor is formed by …….. bonds.
(i) covalent (ii) electrovalent
(iii) co-ordinate (iv) none of the above
A semiconductor has …….. temperature coefficient of resistance.
(i) positive (ii) zero
(iii) negative (iv) none of the above
The most commonly used semiconductor is ……..
(i) germanium (ii) silicon
(iii) carbon (iv) sulphur
A semiconductor has generally …….. valence electrons.
(i)2 (ii) 3
(iii)6 (iv) 4
The resistivity of pure germanium under standard conditions is about ……..
(i) 6 × 104 Ω cm (ii) 60 Ω cm
(iii) 3 × 106 Ω cm (iv) 6 × 10−4 Ω cm
The resistivity of pure silicon is about ……..
(i) 100 Ω cm (ii) 6000 Ω cm
(iii) 3 × 105 Ω cm (iv) 1.6 × 10− 8 Ω cm
When a pure semiconductor is heated, its resistance ……..
(i) goes up (ii) goes down (iii) remains the same (iv) cannot say

The strength of a semiconductor crystal comes from ……..
(i) forces between nuclei
(ii) forces between protons
(iii) electron-pair bonds
(iv) none of the above
When a pentavalent impurity is added to a pure semiconductor, it becomes ……..
(i) an insulator
(ii) an intrinsic semiconductor
(iii) p-type semiconductor
(iv) n-type semiconductor
Addition of pentavalent impurity to a semiconductor creates many ……..
(i) free electrons (ii) holes
(iii) valence electrons (iv) bound electrons
A pentavalent impurity has …….. valence electrons.
(i)3 (ii) 5
(iii)4 (iv) 6
An n-type semiconductor is ……..
(i) positively charged (ii) negatively charged (iii) electrically neutral (iv) none of the above

A trivalent impurity has …….. valence electrons.
(i)4 (ii) 5
(iii)6 (iv) 3
Addition of trivalent impurity to a semiconductor creates many ……..
(i) holes (ii) free electrons
(iii) valence electrons (iv) bound electrons
A hole in a semiconductor is defined as ……..
(i) a free electron
(ii) the incomplete part of an electron pairbond
(iii) a free proton
(iv) a free neutron
The impurity level in an extrinsic semiconductor is about …….. of pure semiconductor.
(i) 10 atoms for 108 atoms
(ii) 1 atom for 108 atoms
(iii) 1 atom for 104 atoms
(iv) 1 atom for 100 atoms
As the doping to a pure semiconductor increases, the bulk resistance of the semiconductor ……..
(i) remains the same
(ii) increases
(iii) decreases
(iv) none of the above
A hole and electron in close proximity would tend to ……..
(i) repel each other
(ii) attract each other
(iii) have no effect on each other
(iv) none of the above
In a semiconductor, current conduction is due ……..
(i) only to holes
(ii) only to free electrons
(iii) to holes and free electrons
(iv) none of the above
The random motion of holes and free electrons due to thermal agitation is called (i) diffusion (ii) pressure (iii) ionisation (iv) none of the above

A forward biased pn junction has a resistance of the ……..
(i) order of Ω (ii) order of kΩ
(iii) order of MΩ (iv) none of the above
The battery connections required to forward bias a pn junction are ……..
(i) +ve terminal to p and −ve terminal to n
(ii) −ve terminal to p and +ve terminal to n
(iii) −ve terminal to p and −ve terminal to n
(iv) none of the above
The barrier voltage at a pn junction for germanium is about ……..
(i) 3.5 V (ii) 3V
(iii) zero (iv) 0.3 V
In the depletion region of a pn junction, there is a shortage of ……….
(i) acceptor ions (ii) holes and electrons
(iii) donor ions (iv) none of the above
A reverse biased pn junction has ……..
(i) very narrow depletion layer
(ii) almost no current
(iii) very low resistance
(iv) large current flow
A pn junction acts as a ……..
(i) controlled switch
(ii) bidirectional switch
(iii) unidirectional switch
(iv) none of the above
A reverse biased pn junction has resistance of the……..
(i) order of Ω (ii) order of kΩ
(iii) order of MΩ (iv) none of the above
The leakage current across a pn junction is due to ……..
(i) minority carriers
(ii) majority carriers
(iii) junction capacitance
(iv) none of the above
When the temperature of an extrinsic semiconductor is increased, the pronounced
effect is on ……..
(i) junction capacitance (ii) minority carriers (iii) majority carriers (iv) none of the above

With forward bias to a pn junction, the width of depletion layer ……..
(i) decreases (ii) increases
(iii) remains the same
(iv) none of the above
The leakage current in a pn junction is of the order of ……..
(i)A (ii) mA
(iii) kA (iv) µA
In an intrinsic semiconductor, the number of free electrons ……..
(i) equals the number of holes
(ii) is greater than the number of holes
(iii) is less than the number of holes
(iv) none of the above
At room temperature, an intrinsic semiconductor has …….. (i) many holes only (ii) a few free electrons and holes (iii) many free electrons only (iv) no holes or free electrons
At absolute temperature, an intrinsic semiconductor has …….. (i) a few free electrons (ii) many holes (iii) many free electrons (iv) no holes or free electrons
At room temperature, an intrinsic silicon crystal acts approximately as ……..
(i) a battery
(ii) a conductor
(iii) an insulator
(iv) a piece of copper wire

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Answers of Mcqs of Pn junction and semiconductor

Answers of PN junction and semiconductor

Chapter Review Topics of PN junctioon and Semiconductor

What do you understand by a semi-conductor ? Discuss some important properties of semiconductors.
Which are the most commonly used semiconductors and why ?
Give the energy band description of semiconductors.
Discuss the effect of temperature on semiconductors.
Give the mechanism of hole current flow in a semiconductor.
What do you understand by intrinsic and extrinsic semiconductors?
What is a pn junction? Explain the formation of a potential barriers in a pn junction.
Discuss the behavior of a pn junction under forward and reverse bias.
Draw and explain the V-I characteristics of a pn junction.
Write short notes on the following :
(i) Breakdown voltage
(ii) Knee voltage
(iii) Limitations in the operating conditions of pn junction

Discussion Questions PN junctioon and Semiconductor

Why is a semiconductor an insulator at ordinary temperature ?
Why are electron carriers present in p-type semiconductor ?
Why is silicon preferred to germanium in the manufacture of semiconductor devices ?
What is the importance of peak inverse voltage ?