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Transistor structure - doping and size of segments
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[add image: circuit symbol of a transistor with base B, collector C, emitter E] The above figure shows the circuit symbol of a transistor. Select the correct statements given below: (A) The transistor has two segments of p-type semiconductor separated by a segment of n-type semiconductor. (B) The emitter is of moderate size and heavily doped. (C) The central segment is thin and lightly doped. (D) The emitter base junction is reverse biased in common emitter amplifier circuit.A (C) and (D)B (A) and (D)C (A) and (B)D (B) and (C)From the arrow direction in the given symbol, the emitter current leaves from the emitter, indicating an NPN transistor (so statement A, which describes a PNP structure, is incorrect for this symbol). Order of doping: E > C >> B; order of size: C > E >> B — so the emitter is of moderate size and heavily doped (B is correct) and the central (base) segment is thin and lightly doped (C is correct). For active mode, the emitter-base junction is forward biased (not reverse biased as stated in D), so D is incorrect. Correct statements: (B) and (C).