Electrical Engineering Objective Questions { Material And Components }

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253. The emitter region in the p-n-p junction transistor is more heavily doped than the base region so that

A. the flow across the base region will be mainly electrons

B. the flow across the base region will be mainly holes

C. base current will be high

D. reacombination will be increased in the base region

254. For a given emitter current, the collector current would be higher if

A. the recombination rate in the base region weher decreased

B. the base region were made wider

C. the minority-carrier mobility in the base region were raduced

D. the emitter region were more lightly doped

255. The emitter current in a junction transistor with normal bias

A. is approximately equal to the base current

B. is equal to the sum of the base current and collector current

C. may be greatly increased by a small change in collector bias

D. is designated 'Co

256. One way in which the operation of an n-p-n transistor differs from that of the p-n-p transistor is that

A. the emitter junction is reverse-biased in the n-p-n

B. the emitter injects minority carriers into the base region of the p-n-p and majority carriers into the base region of the n-p-n

C. the emitter injects holes into the base region of the p-n-p and electrons into the base region of the n-p-n

D. the emitter injects electrons into the base region of the p-n-p and holes into the base region of the n-p-n

257. When emitter current is increased in the n-p-n transistor

A. the base-current increase is approximately equal to the increase in electron current across the emitter junction

B. the collector-current increase is approximately equal to the increase in hole current across the emitter junction

C. the collector-current increase is approximately equal to the increase in electron current across the emitter junction

D. the emitter-current increase is approximately equal to the increase in hole current across the emitter junction

258. A small increase in the collector reverse bias will cause

A. a large increase in emitter current

B. a large increase in collector current

C. very little change in collector reverse saturation current

D. a large decrease in collector current

259. Base current in a p-n-p transistor with normal bias is :

A. small compared to the emitter current

B. approximately equal to the emitter current

C. much larger than the emitter current (z) zero

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