MCQOPTIONS
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MCQOPTIONS
This section includes 142 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering Physics knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
Mobility of electrons in a semiconductor is defined as the ratio of their drift velocity to the applied electric field. If, for an n-type semiconductor, the density of electrons is 1019 m-3 and their mobility is 1.6 m2/(V.s) then the resistivity of the semiconductor contribution of holes is ignored) is close to: |
| A. | 2 Ωm |
| B. | 4 Ωm |
| C. | 0.4 Ωm |
| D. | 0.2 Ωm |
| Answer» D. 0.2 Ωm | |
| 102. |
At much lower temperature, semiconductors behave as: |
| A. | Semiconductors only |
| B. | Conductors |
| C. | Insulators |
| D. | Conductors or insulator |
| Answer» D. Conductors or insulator | |
| 103. |
A bar of Gallium Arsenide (GaAs) is doped with Silicon such that the Silicon atoms occupy Gallium and Arsenic sites in the GaAs crystal. Which one of the following statements is true? |
| A. | Silicon atoms act as p-type dopants in Arsenic sites and n-type dopants in Gallium sites |
| B. | Silicon atoms act as n-type dopants in Arsenic sites and p-type dopants in Gallium sites |
| C. | Silicon atoms act as p-type dopants in Arsenic as well as Gallium sites |
| D. | Silicon atoms act as n-type dopants in Arsenic as well as Gallium sites |
| Answer» B. Silicon atoms act as n-type dopants in Arsenic sites and p-type dopants in Gallium sites | |
| 104. |
For thermionic emission _____. |
| A. | a material with high work function is preferable |
| B. | a material with low work function is preferable |
| C. | the work function of the material has no importance |
| D. | None of these |
| Answer» C. the work function of the material has no importance | |
| 105. |
__________ is a pentavalent dopant |
| A. | Indium |
| B. | Boron |
| C. | Arsenic |
| D. | Aluminium |
| Answer» D. Aluminium | |
| 106. |
In a bcc structure, the packing fraction is: |
| A. | \(\sqrt{2} \ \pi/6\) |
| B. | \(\pi/3\) |
| C. | \((\pi\sqrt{3})/8\) |
| D. | \(\sqrt{5} \ \pi/6\) |
| Answer» D. \(\sqrt{5} \ \pi/6\) | |
| 107. |
Metals are good conductors of heat because they- |
| A. | Contain a glut of free electrons |
| B. | Contain very few free electrons |
| C. | Have high density |
| D. | Atoms-are relatively far apart |
| Answer» B. Contain very few free electrons | |
| 108. |
Pure Semiconductor Silicon Doped with Boron forms |
| A. | pn-Type Semiconductor |
| B. | n-type Semiconductor |
| C. | p-type Semiconductor |
| D. | np-type semiconductor |
| Answer» D. np-type semiconductor | |
| 109. |
Consider two energy levels: E1, E eV above the Fermi Level and E2, E eV below the Fermi Level. P1 and P2 are respectively the probabilities of E1 being occupied by an electron and E2 being empty. Then |
| A. | P1 > P2 |
| B. | P1 = P2 |
| C. | P1 < P2 |
| D. | P1 & P2 depends on number of free electrons |
| Answer» C. P1 < P2 | |
| 110. |
For a transistor in common emitter configuration _________ is the ratio of the change in collector current to the change in base current at a constant collecto-emitter voltage (VCE) when the transistor is in active state. |
| A. | Current amplification factor |
| B. | Output resistance |
| C. | Input resistance |
| D. | Voltage gain |
| Answer» B. Output resistance | |
| 111. |
If the number of valence electrons in an atom is more than 4, what is the substance called? |
| A. | a conductor |
| B. | neutral |
| C. | a bad conductor |
| D. | a semiconductor |
| Answer» D. a semiconductor | |
| 112. |
Gold is an example of which of the following? |
| A. | Conductor |
| B. | Semiconductor |
| C. | Magnet |
| D. | Insulator |
| Answer» B. Semiconductor | |
| 113. |
At absolute zero temperature, the intrinsic semiconductor material is: |
| A. | perfect insulator |
| B. | superconducting |
| C. | conducting |
| D. | slightly conducting |
| Answer» B. superconducting | |
| 114. |
Doping materials are called impurities because they |
| A. | decrease the number of charge carriers |
| B. | change the chemical properties of semiconductors |
| C. | make semiconductors less than 100 percent pure |
| D. | alter the crystal structures of pure semiconductors |
| Answer» E. | |
| 115. |
An extrinsic semiconductor has: |
| A. | more number of free electrons than holes |
| B. | more number of holes than electrons |
| C. | either more holes or more free electrons |
| D. | equal number of holes and free electrons |
| Answer» D. equal number of holes and free electrons | |
| 116. |
In n-type silicon, each atom contributes |
| A. | 1 free electron |
| B. | 2 free electron |
| C. | 3 free electron |
| D. | 4 free electron |
| Answer» B. 2 free electron | |
| 117. |
If the number of valence electrons in an atom is less than 4, what is the substance called? |
| A. | a conductor |
| B. | a semiconductor |
| C. | neutral |
| D. | a bad conductor |
| Answer» B. a semiconductor | |
| 118. |
an n-type semiconductor is_______. |
| A. | Positively charged |
| B. | negatively charged |
| C. | electrically neutral |
| D. | not used in semiconductor devices |
| Answer» D. not used in semiconductor devices | |
| 119. |
at room temperature intrinsic carrier concentration is higher in germanium than in silicon because __________. |
| A. | Carrier mobilities are higher Ge than in Si |
| B. | energy gap in Ge is smaller than that in Si |
| C. | Atomic number of Ge is larger than in Si |
| D. | Atomic weight of Ge is larger than in Si |
| Answer» C. Atomic number of Ge is larger than in Si | |
| 120. |
Polystyrene is an example of _______. |
| A. | a semiconductor |
| B. | a superconductor |
| C. | a conductor |
| D. | an insulator |
| Answer» E. | |
| 121. |
In the depletion region of an unbiased P.N. junction diode are only |
| A. | Electrons |
| B. | Holes |
| C. | Both electrons and holes |
| D. | Only fixed ions |
| Answer» E. | |
| 122. |
Direction: Question consists of two statements, one labeled as the 'Assertion (A)' and the other as 'Reason (R)'. Examine these two statements carefully and select the answer to this question using the codes given below:Assertion (A): At very high temperatures, both p and n-type semiconductors behave as intrinsic semiconductors.Reason (R): In an n-type semiconductor the majority carriers are electrons and in a p-type semiconductor the majority carriers are holes, whereas in an intrinsic semiconductor the number of holes and electrons are equal. |
| A. | Both A and R are individually true and R is the correct explanation of A |
| B. | Both A and R are individually true but R is not the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» C. A is true but R is false | |
| 123. |
A small amount of phosphorus is added to silicon so that there are 2.5 × 1017 conduction electrons per cubic meter and 9.0 × 1014 holes per cubic meter. Let μe = 0.13 m2/V.s and μh = 0.05 m2/V.s. The resistivity in Omega m will be |
| A. | 5.2072 |
| B. | 192.042 |
| C. | 129.02 |
| D. | 0 |
| Answer» C. 129.02 | |
| 124. |
An NPN transistor is used in common emitter configuration as an amplifier with 1 kΩ load resistance. Signal voltage of 10 mV is applied across the base-emitter. This produces a 3 mA change in the collector current and 15 μA change in the base current of the amplifier. The input resistance and voltage gain are: |
| A. | 0.33 kΩ, 1.5 |
| B. | 0.67 kΩ, 300 |
| C. | 0.67 kΩ, 200 |
| D. | 0.33 kΩ, 300 |
| Answer» C. 0.67 kΩ, 200 | |
| 125. |
In an n-type doped semiconductor, the Fermi level is |
| A. | Closer to the conduction band edge |
| B. | Closer to the valence band edge |
| C. | Exactly at the middle of the bandgap |
| D. | Within the conduction band |
| Answer» B. Closer to the valence band edge | |
| 126. |
Mica is a: |
| A. | insulating and dielectric material |
| B. | dielectric material but not an insulator |
| C. | insulating material but not dielectric |
| D. | magnetic material |
| Answer» B. dielectric material but not an insulator | |
| 127. |
In ______________the conduction band overlaps on the valence band. |
| A. | elemental semiconductors |
| B. | compound semiconductors |
| C. | metallic conductors |
| D. | insulators |
| Answer» D. insulators | |
| 128. |
In the figure, given that VBB supply can vary from 0 to 5.0V, VCC = 5 V, βDC = 200, RB = 100 k Ω, RC = 1 kΩ and VBE = 1.0 V. The minimum base current and the input voltage at which the transistor will go to saturation, will be, respectively |
| A. | 25 μA and 2.8 V |
| B. | 25 μA and 3.5 V |
| C. | 20 μA and 3.5 V |
| D. | 20 μA and 0.8 V |
| Answer» C. 20 μA and 3.5 V | |
| 129. |
In semi-conductor terminology, doping is a process of: |
| A. | Purifying semiconductor material |
| B. | Increasing impurity percentage |
| C. | Removal of foreign atoms |
| D. | Increasing the bias potential |
| Answer» C. Removal of foreign atoms | |
| 130. |
Match the following: a) P-N Junction diodei)b) Zener diodeii) c) Schottky diodeiii) d) Tunnel diodeiv) |
| A. | a-iii, b-iv, c-ii, d-i |
| B. | a-iii, b-ii, c-i, d-iv |
| C. | a-i, b-ii, c-iii, d-iv |
| D. | a-ii, b-iii, c-iv, d-i |
| Answer» C. a-i, b-ii, c-iii, d-iv | |
| 131. |
Pure metals generally have _____. |
| A. | high conductivity and low temperature coefficient |
| B. | high conductivity and large temperature coefficient |
| C. | low conductivity and zero temperature coefficient |
| D. | low conductivity and high temperature coefficient |
| Answer» C. low conductivity and zero temperature coefficient | |
| 132. |
A p-type of semiconductor is |
| A. | uncharged |
| B. | +vely charged |
| C. | -vely charged |
| D. | uncharged only at 0°C |
| Answer» B. +vely charged | |
| 133. |
WHAT_TYPE_OF_MATERIAL_IS_OBTAINED_WHEN_AN_INTRINSIC_SEMICONDUCTOR_IS_DOPED_WITH_TRIVALENT_IMPURITY??$ |
| A. | Extrinsic semiconductor |
| B. | Insulator |
| C. | N-type semiconductor |
| D. | P-type semiconductor |
| Answer» E. | |
| 134. |
What type of material is obtained when an intrinsic semiconductor is doped with pentavalent impurity? |
| A. | N-type semiconductor |
| B. | Extrinsic semiconductor |
| C. | P-type semiconductor |
| D. | Insulator |
| Answer» B. Extrinsic semiconductor | |
| 135. |
How is charge carriers produced in intrinsic semiconductors? |
| A. | By pure atoms |
| B. | By electrons |
| C. | By impure atoms |
| D. | By holes |
| Answer» D. By holes | |
| 136. |
Compound semiconductors are also known as direct band gap semiconductors. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 137. |
Which column elements are combined to make compound semiconductors? |
| A. | First and fourth |
| B. | Fifth and sixth |
| C. | Second and fourth |
| D. | Third and fifth |
| Answer» E. | |
| 138. |
Which of the following is known as indirect band gap semiconductors? |
| A. | Germanium |
| B. | Nickel |
| C. | Platinum |
| D. | Carbon |
| Answer» B. Nickel | |
| 139. |
What are the charge carriers in semiconductors? |
| A. | Electrons and holes |
| B. | Electrons |
| C. | Holes |
| D. | Charges |
| Answer» B. Electrons | |
| 140. |
How is the resistance of semiconductor classified? |
| A. | High resistance |
| B. | Positive temperature co-efficient |
| C. | Negative temperature co-efficient |
| D. | Low resistance |
| Answer» D. Low resistance | |
| 141. |
Semiconductor acts as an insulator in the presence of impurities. |
| A. | True |
| B. | False |
| Answer» C. | |
| 142. |
How does a semiconductor behave at absolute zero? |
| A. | Conductor |
| B. | Insulator |
| C. | Semiconductor |
| D. | Protection device |
| Answer» C. Semiconductor | |