Electrical Engineering Objective Questions { Material And Components }

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218. Field-effect transistors

A. use a high-concentration emitter junction

B. use a forward-biased p-n junction

C. have a very high input resistance

D. depend on minority-carrier flow

219. In the four-point probe method of determining resistivity

A. the sample must be intrinsic

B. current flows in only a small area of the sample.

C. one probe point must inject minority carriers

D. the current source is connected to the two inner probes

220. Advantage of the four-point-probe method is that

A. gives the average resistivity of the sample

B. eliminates the use of current flow

C. gives the resistivity at a localized region on the sample

D. injects excess minority carriers

221. Requirement of the four-point-probe method is that

A. a fairly high current should be used

B. the cross-sectional area along with sample must be constant

C. one of the contacts must inject minority carriers

D. the current must be low/

222. Minority-carrier mobility may be determined if we know

A. voltage across and current through the sample

B. the speed and time of travel between two points

C. the speed of travel and the voltage between two points

D. the resistance and voltage between two points

223. A electrically neutral semiconductor has

A. no free charges

B. no majority carriers

C. equal amounts of positive and negative charge

D. no minority carriers

224. When a normal atom looses an electron, the atom

A. becomes a positive ion

B. becomes a negative ion

C. becomes electrically neutral

D. is then free to move about

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