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Electronics Engineering Objective Questions { Semiconductor Physics and Diodes }

211. The concentration of minority carriers in an extrinsic semiconductor under equilibrium is
A. directly proportional to the doping concentration
B. inversely proportional to the doping concentration
C. directly proportional to the intrinsic concentration
D. inversely proportipnal to the intrinsic concentration
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212. Under low level injection assumption, the injected minority carrier current for an extrinsic semiconductor is essentially the
A. diffusion current
B. drift current
C. recombination current
D. induced current
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213. The majority carriers in an n-type semiconductor have an average drift velocity V in a direction perpendicular to a uniform magnetic field B. The electric field E induced due to Hall effect acts in the direction.
A. V x B
B. B x V
C. along V
D. opposite to V
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214.  A heavily doped n-type semiconductor has the following data Hole-electron mobility ratio : 0.4Doping concentration : 4.2 x 108 atoms/m3 Intrinsic concentration : 1.5 x 104 atoms/m3 The ratio of conductance of the n-type semiconductor to that of the intrinsic semiconductor of same material and at the same temperature is given by
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215. The electron and hole concentration in an intrinsic semiconductor are ni per cm3 at 300 K. Now, if acceptor impurities are introduced with a concentration of NA per cm3 (where NA >> ni), the electron concentration per cm3 at 300 K will be
A. n.
B. NA 2 n
D. ni
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216. A p+ n junction has built-in potential of 0.8 V. The depletion layer width at a reverse bias of 1.2 V is 2 pm. For a reverse bias of 7.2 V, the depletion layer width will be
A. 4 pm
B. 4.9 pm
C. 8 p.m
D. 12 1.1M
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