InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 201. |
The cause of the potential barrier in a p-n diode is:A. depletion of positive charges near the junction.B. concentration of positive charges near the junctionC. depletion of negative charges near the junctionD. concentration of positive and negative charges near the junction. |
| Answer» Correct Answer - D | |
| 202. |
Colour of light emitted by LED depends uponA. its forward biasB. its reverse biasC. the band gap of the material of the semiconductorD. its size |
| Answer» Correct Answer - C | |
| 203. |
To measure the resistance of a galvanometer by half deflection method, a shunt is connected to the galvanometer . The shunt isA. to bring the defection of galvanometer within the scaleB. to minimize power lossC. because high resistances are easily availableD. none of these |
| Answer» Correct Answer - A | |
| 204. |
Potentiometer wire is made of manganin because it hasA. High specific resistace, low temperature coefficientB. low specific resistace, high temperature coefficientC. low specific resistance, low temperature coefficientD. high specific resistance, high temperature coefficient |
| Answer» Correct Answer - A | |
| 205. |
Which of the following statements is wrong?A. To increase sensitivity of a potentiometer increase current through potentiometer wireB. to increase sensitivity increase external resistance in battery circuit connected to potentiometerC. to increase sensitivity increase battery voltageD. to increase sensitivity increase the emf of battery |
| Answer» Correct Answer - B | |
| 206. |
which one of the following statements is wrong ?A. The resistance of intrinsic semiconductors decreases with increase of temperatureB. Doping pure Si with trivalent impurities gives p-type semiconductorsC. The majority carriers in n-type semiconductors are holesD. A p-n junction can act as rectifier |
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Answer» Correct Answer - C Wrong statement : Holes are the majority carriers in n-type semiconductors. Correct statement : Electrons are the majority carriers . |
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| 207. |
The depletion layer in `P-N` junction region is caused byA. drift of holesB. diffusion of free charge carriesC. migration of impurity ionsD. drift of electrons |
| Answer» Correct Answer - B | |
| 208. |
The depletion region of a P-N diode, under open circuit condition containsA. ElectronsB. HolesC. Unmasked immobile impurity ionsD. Impurity atoms |
| Answer» Correct Answer - C | |
| 209. |
The potential barrier in p-n diode is due to : (A) depletion of positive charges near the junction (B) accumulation of positive charges near the junction (C) depletion of negative charges near the junction, (D) accumulation of positive and negative charges near the junction |
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Answer» Correct answer is (D) accumulation of positive and negative charges near the junction |
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| 210. |
The energy band gap is maximum inA. metalsB. super conductorsC. insulatorsD. semiconductors |
| Answer» Correct Answer - C | |
| 211. |
Which is the wrong statement in following sentence? A device in which P and N type semiconductors are used is more useful then a cacuum tube because-A. power is not necessary to heat the filamentB. it is more stableC. very less heat is producted in itD. its efficiency is high due to a high voltage drop across the junction. |
| Answer» Correct Answer - D | |
| 212. |
What is the importance of energy gap in a semiconductor? |
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Answer» 1. The gap between the bottom of the conduction band and the top of the valence band is called the energy gap or the band gap. 2. This band gap is present only in semiconductors and insulators. 3. Magnitude of the band gap plays a very important role in the electronic properties of a solid. 4. Band gap in semiconductors is of the order of 1 eV. 5. If electrons in valence band of a semiconductor are provided with energy more than band gap energy (in the form of thermal energy or electrical energy), then the electrons get excited and occupy energy levels in conduction band. These electrons can easily take part in conduction. |
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| 213. |
The most commonly used semiconductors areA. wool and glassB. copper and brassC. glass and eboniteD. germanium and silicon |
| Answer» Correct Answer - D | |
| 214. |
The free electron model of metallic solid does not explainA. range of resistivitiesB. behaviour of insulatorsC. behaviour of semiconductorsD. creation of holes on crytstals |
| Answer» Correct Answer - A | |
| 215. |
INTRINSIC SEMICONDUCTORSA. conduction band of an intrinsic semiconductorB. conduction band of an extrinsic semiconductorC. valance bands of intrinsic and extrinsic semiconductorsD. Super conductors |
| Answer» Correct Answer - C | |
| 216. |
The conductivity of semiconductorsA. is independent of temperatureB. decrease with increase of temperatureC. increases with increases of temperatureD. varies unpredictably with temperature |
| Answer» Correct Answer - C | |
| 217. |
Mention the broad classification of semiconductors along with examples. |
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Answer» A broad classification of semiconductors can be: 1. Elemental semiconductors: Silicon, germanium 2. Compound Semiconductors: Cadmium sulphide, zinc sulphide, etc. 3. Organic Semiconductors: Anthracene, doped pthalocyanines, polyaniline etc. |
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| 218. |
What are some electrical properties of semiconductors? |
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Answer» 1. Electrical properties of semiconductors are different from metals and insulators due to their unique conduction mechanism. 2. The electronic configuration of the elemental semiconductors plays a very important role in their electrical properties. 3. They are from the fourth group of elements in the periodic table. 4. They have a valence of four. 5. Their atoms are bonded by covalent bonds. At absolute zero temperature, all the covalent bonds are completely satisfied in a single crystal of pure semiconductor like silicon or germanium. |
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| 219. |
Which element would you use as an impurity to make germanium an n-type semiconductor? |
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Answer» Germanium can be made an n-type semiconductor by doping it with pentavalent impurity, like phosphorus (P), arsenic (As) or antimony (Sb). |
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| 220. |
In germanium crystal, a hole is provided by an impurity ofA. covalentB. monovalentC. trivalentD. tetravalent |
| Answer» Correct Answer - C | |
| 221. |
Statement 1: Doping concentration is maximum in emitter in transistor. Statement 2: Maximum number of electrons flows from emitter to base in n-p-n transistor.A. Both statement-1 and statement-2 are true, and statement-2 is the correct explanation of statement 1.B. Both statement-1 and statement-2 are true but statement-2 is not the correct explanation of statement-2C. Statement-1 is true but statement-2 is false.D. Statement-1 is false but statement-2 true. |
| Answer» Correct Answer - B | |
| 222. |
Statement-1: In semiconductors current is obtained due to motion of electrons and holes. Statement-2: Breaking up of covalent bond produces holes in valence band and electrons in conduction band.A. Both statement-1 and statement-2 are true, and statement-2 is the correct explanation of statement 1.B. Both statement-1 and statement-2 are true but statement-2 is not the correct explanation of statement-2C. Statement-1 is true but statement-2 is false.D. Statement-1 is false but statement-2 true. |
| Answer» Correct Answer - A | |
| 223. |
Holes are the majority carries in Intrinsic Semiconductors.(a) True(b) FalseThis question was addressed to me in an international level competition.My question is taken from Classification of Semiconductors in division Semiconductors of Engineering Physics II |
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Answer» Right option is (b) False The explanation: A pure semiconductor is called an intrinsic semiconductor. Hence, in this case, the number of electrons and holes are same, as the electron that moves out of its position leaves a hole behind. Hence, the concentration of holes and electrons is the same in an intrinsic semiconductor. |
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| 224. |
The energy band gap is maximum inA. copperB. an insulatorC. germaniumD. a super conductor |
| Answer» Correct Answer - B | |
| 225. |
Solids having highest energy level partially filled with electrons areA. an insulatorB. a semiconductorC. a conductorD. none of these |
| Answer» Correct Answer - C | |
| 226. |
In a pure conductor, the value of the forbidden energy gap isA. 0.5 evB. 1.1 evC. zeroD. 2.3 ev |
| Answer» Correct Answer - C | |
| 227. |
If there is no hole current in a substance, if must beA. an insulatorB. a conductorC. an n-type semiconductorD. a p-type semiconductor |
| Answer» Correct Answer - B | |
| 228. |
A potential difference of 2V is applied between the opposite faces of a Ge crystal plate of area `1cm^(2)` and thickness 0.5 mm. if the concentration of electrons in Ge is `2xx10^(19)//m^(3)` and mobilities of electrons and holes are 0.36 `(m^(2))/("volt-sec") and 0.14(m^(2))/("volt-sec")` respectivity, then the current flowing through the plate will be-A. 0.25 AB. 0.45 AC. 0.56 AD. 0.64 A |
| Answer» Correct Answer - D | |
| 229. |
When all the inputs of a NAND gate are connected together, the resulting circuit is :-A. a NOT gateB. an AND gateC. an OR gateD. a NOR gate |
| Answer» Correct Answer - A | |
| 230. |
Which of the following logic gates is an universal gate?A. ORB. NOTC. ANDD. NOR |
| Answer» Correct Answer - D | |
| 231. |
Which of the following gates will have an output of `1`? A. B. C. D. |
| Answer» Correct Answer - C | |
| 232. |
If `A` and `B` are two inputs in `AND` gate, then `AND` gate has an output of `1` when the values of `A` and `B` areA. A=0, B=0B. A=1,B=1C. A=1,B=0D. A=0,B=1 |
| Answer» Correct Answer - B | |
| 233. |
How many NOR gates are used to form an AND gateA. 1B. 2C. 3D. 4 |
| Answer» Correct Answer - C | |
| 234. |
Which of the following gates will have an output of 1 :- A. (a) and (b)B. (b) and (c)C. (c) and (d)D. (a) and (d) |
| Answer» Correct Answer - C | |
| 235. |
The truth table shown below is for which of the following gate :- `{:(A,B,Y),(1,1,0),(1,0,0),(0,1,0),(0,0,1):}`A. ANDB. NANDC. XORD. NOR |
| Answer» Correct Answer - D | |
| 236. |
The symbol represents :- A. NAND gateB. OR gateC. AND gateD. NOR gate |
| Answer» Correct Answer - A | |
| 237. |
In a common base configuration (transistor circuit) `I_(E)=1mA, I_(C)=0.95mA`. The value of base current isA. 195 mAB. 0.05 mAC. 105 mAD. 0.95 mA |
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Answer» Correct Answer - B For a common base transistor, `I_(E)=I_(B)+I_(C )` `1mA=I_(B)=0.95mA` `I_(B)=0.05mA` |
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| 238. |
For a transistor `I_(e) = 25 mA and I_(b) = 1mA`. The value of current gain `alpha` will be :-A. `(25)/(24)`B. `(24)/(25)`C. `(25)/(26)`D. `(26)/(25)` |
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Answer» Correct Answer - B `alpha=(I_(C))/(I_(E))=(I_(E)-I_(B))/(I_(E))=(25-1)/(25)=(24)/(25)` |
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| 239. |
A transistor has an `alpha = 0.95` It has change in emitter current of 100 mili-ampere, then the change in collector current is :-A. 95 mAB. 99.05 mAC. 0.95 mAD. 100 mA |
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Answer» Correct Answer - A `alpha=(DeltaI_(C))/(DeltaI_(E))rArr DeltaI_(C)=alpha DeltaI_(E)=0.95xx100 mA=95mA` |
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| 240. |
A transistor have a `beta` a equal to 80 has a change in base current of `250mu` ampere, then the change in collector current isA. `80X" "250muA`B. `(250-80)muA`C. `(250+80)muA`D. `(250//80muA)` |
| Answer» Correct Answer - A | |
| 241. |
The cut-in voltage for silicon diode is approximatelyA. 0.2 VB. 0.6 V and 0.9 VC. 1.1 VD. 1.4 V |
| Answer» Correct Answer - B | |
| 242. |
In an unbiased p-n junction,A. p and n both are at same potentialB. high potential at n side and low potential at p-sideC. high potential at p side and low, potienial at n sideD. low potential at n side and zero potential at p side |
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Answer» Correct Answer - B In an unbiased p-n junction, there is only the internal barrier potential, in which n side is at a higher potential and p side is at a lower potential. |
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| 243. |
The diode shown in the circuit is a silicon diode. The potential difference between the points `A` and `B` will be A. 6 VB. 0.6 VC. 0. 7 VD. 0 V |
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Answer» Correct Answer - A The diode is reverse biased. No current flows in the circuit. `therefore` P.D. of 6 V acts across only the diode or between the points A and B. |
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| 244. |
For a transistor the parameter `beta=99`. The value of the parameter `alpha` isA. 0.1B. 1C. 0.9D. 9 |
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Answer» Correct Answer - D Relation between `alpha` and `beta` is given by `alpha=(beta)/(1+beta)` `0.9=(beta)/(1+beta) rArr beta=9` |
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| 245. |
Identify which of the following diagrams represent the internal construction of the coils wound in a resistance box or PO box ?A. B. C. D. |
| Answer» Correct Answer - D | |
| 246. |
Using meter bridge, it is advised to obtain the null point in the middle of bridge wire. Why?A. reduces systematic error as well as random errorB. reduces systematic error but not the random error.C. Reduces random error but not the systemeatic errorD. reduces neither systematic error nor the random error. |
| Answer» Correct Answer - A | |
| 247. |
In the laboratory method for measuring the latent heat of stream, the steam is passed through the device shown below. The function of the device isA. to prevent condensed steam from reaching the calorimenterB. to reduce the pressure the steamC. to ensure that thhe pressure of the steam is equal to the atmospheric pressureD. to control the rate of flow of steam |
| Answer» Correct Answer - A | |
| 248. |
In a p-n junction with open ends,(a) there is no systematic motion of charge carriers(b) hole and conduction electrons systematically go from the p-side to the n-side to the p-side respectively(c) there is no net charge transfer between the two sides (d) there is a constant electric field near the junction. |
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Answer» (b) hole and conduction electrons systematically go from the p side to the n-side to the p-side respectively (c) there is no net charge transfer between the two sides (d) there is a constant electric field near the junction. |
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| 249. |
What is the value of the output X in the following logic gate circuit ? A. X=A+B+AB. X=A.(A+B)C. X=A+(A.B)D. X=ABC |
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Answer» Correct Answer - B The output of the OR gate is A+ B. For the AND gate, the inputs are A and A+ B. `therefore` Output X =A(A + B) |
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| 250. |
How many `NAND` gate are used to from `AND` gate?A. 2B. 3C. 4D. 1 |
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Answer» Correct Answer - A 2 NAND gates are required to form an AND gate. The output of a NAND gate is inverted by a NOT gate to get an AND gate |
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