RRB JE 2019 Electronics Materials (Conductor, Semiconductor and Insulator)

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Randolph Holt
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1 RRB JE 2019 Electronics Materials (Conductor, Semiconductor and Insulator) [1 ]

2 1. Nucleus is made of न भभक बन ह त ह : - a) Electrons and Protons b) Photons and neutrons c) Photons and neutrons d) Photons and electrons 2. Atom of any element is ककस तत वn क परम ण ह त ह : - a) Positively charged b) Negatively charged c) Positively or negatively charged d) Not charged 3. Conduction of electricity through conductor takes place by क डक टर क म ध यम स भबजल क स च लन ह त ह a) Protons b) Neutrons c) Bound electrons d) Free electrons 4. Intrinsic semiconductor at room temperature will have.. a) Electrons b) Holes c) Both electrons and holes d) None of the above [2 ]

3 5. Intrinsic semiconductor at 0 K will have.. available for conduction. a) Electrons b) Holes c) Both electrons and holes d) Nothing 6. At room temperature N type material will have a) More of electrons b) More of holes c) Equal number of electrons and holes d) None 7. A room temperature P type material will have. a) More of electrons b) More of holes c) Equal number of electrons and holes d) None 8. One ev of energy is equivalent to a) 2.0 ers b) joule c) Joule d) Joule [3 ]

4 9. Which of the following statements is incorrect regarding conduction band? a) It lies below the valence band b) It may be either empty or partially filled c) It is lowest unfilled energy band d) It represents the energy of conduction electrons. 10. The forbidden band in germanium at 0 K is a) 0.03 ev b) ev c) 1.5 ev d) 2.0 ev 11. Donor type semi conductor is formed by adding impurity of valency. a) 2 b) 3 c) 4 d) Fermi level represents the energy level with probability of its occupation of Fermi स तर इसक कब ज क स भ वन क स थ ऊज स तर क प रभतभनभ त व करत ह a) Zero b) 25 Percent c) 50 Percent d) 100 Percent [4 ]

5 13. Consider the energy level diagram of an intrinsic semiconductor. The Fermi level lies in the a) Valence band b) Forbidden gap c) Conduction band or d) It can be at any of the above locations depending upon the doping concentration and temperature. 14. A semiconductor has. Temperature co efficient of resistance. a) Zero b) Positive c) Negative d) None of the above 15. A semiconductor in its purest form is called. a) Insulator b) Superconductor c) Intrinsic semiconductor d) Extrinsic semiconductor 16. An electron in the conduction band a) Is always chargeless b) Has tendency to leave the atom c) Has lower energy than an electron in the valence band. d) Has higher energy than and electron in the valence band. [5 ]

6 17... has the highest mobility. a) Electron b) Positive ions c) Negative ions d) Neutrons 18. The donor impurity must have only.. valence electrons. a) Two b) Three c) Four d) Five 19. Acceptor type impurities.. a) Can be added to silicon but not to germanium b) Create excess electrons c) Must have three valence electrons. d) Must have five valence electrons. 20. Which of the following cannot exist outside a semiconductor? इनम स क न स स म क डक टuर क ब हर नह रहत ह a) Hole b) Electron c) Both (a) and (b) d) None of the above [6 ]

7 21. In a N type semiconductor, the position of the Fermi level N type अर द च लक म फम स तtर क भस थभत ह त ह : - a) Is at the centre of the energy gap b) Is lower than the centre of energy gap c) Is higher than the centre of energy gap d) Can be anywhere depending upon the doping concentration. 22. Fermi energy is the amount of energy which a) A valence electron can have at room temperature b) Must be given to a hole to move it to valence band c) A hole can have at room temperature. d) Must be given to an electron to move it to conduction band. 23. An intrinsic semiconductor has the following properties : 1. Its electron concentration equals its hole concentration. 2. Its carrier density increases with temperature. 3. Its conductivity decrease with temperature. Which of these statements are correct? a) 1,2 and 3 b) 2 and 3 only c) 1 and 3 only d) 1 and 2 only [7 ]

8 24. A hole in a semiconductor has 1. Positive charge equal to the electron charge. 2. Positive mass equal to the mass of the electron. 3. An effective mass greater than the effective mass of electron. 4. Negative mass and positive charge equal to the charge in nucleus. Which of these statements are correct? a) 1,2,3 and 4 b) 1 and 3 only c) 2 and 4 only d) 3 and 4 only 25. Medium doping in Silicon and Germanium corresponds to impurity of the order of a) 1 part in 10 6 b) 1 part in 10 5 c) 1 part in 10 4 d) 1 part in At very high temperature, an n type semiconductor behave like a) A p type semiconductor b) An intrinsic semiconductor c) A superconductor d) An n type semiconductor [8 ]

9 27. The Fermi level in a p type semiconductor lies close to a) Top of the valence band b) Bottom of the valence band c) Top of the conduction band d) Bottom of the conduction band 28. Covalent bond energy in germanium is about a) 7.4 ev b) 3.1 ev c) 3.4 ev d) 0.7 ev 29. The energy gap in the energy band structure of a material is 9 ev at room temperature. The material is a) Semiconductor b) Conductor c) Metal d) Insulator 30. By doping germanium with Gallium, the types of semiconductors formed are : 1. N type 2. P type 3. Intrinsic 4. Extrinsic [9 ]

10 Which of the above are correct : - a) 1 and 4 b) 2 and 4 c) 1 and 3 d) 2 and An n type can be formed by adding impurity of 1. Phosphorous 2. Arsenic 3. Boron 4. Aluminum Which of the above are correct? a) 1 and 2 b) 2 and 3 c) 3 and 4 d) 1 and 4 [10 ]

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CLASS 12th. Semiconductors

CLASS 12th. Semiconductors CLASS 12th Semiconductors 01. Distinction Between Metals, Insulators and Semi-Conductors Metals are good conductors of electricity, insulators do not conduct electricity, while the semiconductors have