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A transistor in good condition has its three terminals labeled P, Q, and R. When checked with a multimeter, there is no conduction between P and Q. However, if the negative lead of the meter is connected to R and the positive lead is connected to either P or Q, the meter shows some resistance. What can be concluded about the transistor?
- It is an npn transistor with R as the base
- It is a pnp transistor with R as the base
- It is a pnp transistor with R as the emitter
- It is an npn transistor with R as the collector
Correct answer: It is a pnp transistor with R as the base
Solution
With the meter's positive (red) lead on P or Q and the negative (black) lead on R, both junctions conduct, so P and Q are p-type (anodes) and R is the common n-type region. Two p regions sharing one n region is a PNP transistor with R as the base.
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