225. The potential barrier at a p-n junction is due to the charges on either side of the junction. These charges are
A. Majority carriers
B. Minority carriers
C. Both majority and minority carriers
D. Fixed donor and acceptor ions
226. In an unbiased p-n junction, the junction current at equilibrium is
A. due to diffusion of majority carreirs only
B. due to diffusion of minority carriers only
C. zero, because no charges are crossing the junction
D. zero, because equal but opposite currents are crossing the juction
227. Holes diffuse from the p-region to the n-region because
A. there is greater connectration of holes in the region
B. they are swept across the junction by the potential difference
C. the free electrons in the n-region attract them
D. none of these
228. When a hole diffused from the p-region to the n-region, it
A. becomes a majority carrier in the n-region
B. becomes a minority carrier in the n-region
C. lowers the potential barrier
D. raises the potential barrier
229. If the junction current is zero, this means
A. the potential barrier has disappeared
B. the number of holes diffusing from the p region equals the number of electrons diffusing from the n-region
C. there are no carriers crossing the junction
D. the number of majority carriers crossing the junction equals the number of minority carriers crossing the junction
230. The junction barrier offers opposition only to
A. holes in the p-region
B. free electrons in the n-region
C. minority carriers in both the regions
D. majority carriers in both the regions
231. A reverse bias
A. lowers the potential barrier
B. raises the potential barrier
C. greatly increased the majority-carrier current
D. greatly increased the minority-carreir current
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