What bias conditions must be present for the normal operation of a transistor amplifier? A)the emitter base junction must be reverse biased, and the collector base junction must be forward biased. B)the emitter base junction must be forward biased, and the collector base junction must be reverse biased. C)both junctions must be reverse biased. D)both junctions must be forward biased.
If the collector were forward biased, the transistor would conduct like a shorted wire.
Your posting questions without any thought posted leads me suspiciously that you are looking mostly for answers, not understanding. I don't have time to provide answers to all questions, but I will willingly help clarify understanding.
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The answer is B.
The correct answer is A) the emitter base junction must be reverse biased, and the collector base junction must be forward biased.
To understand why, let's break it down:
A transistor is composed of two pn junctions - the emitter base junction and the collector base junction. Biasing is the process of applying a voltage to these junctions to establish the operating conditions of the transistor.
In a transistor amplifier, the emitter base junction is reverse biased, meaning the emitter is at a more negative potential than the base. This reverse bias establishes the required barrier for the majority charge carriers (electrons in an NPN transistor) to cross the junction and enter the base region. This allows a small current to flow from the emitter to the base, known as the base current.
Meanwhile, the collector base junction is forward biased, meaning the collector is at a more positive potential than the base. This forward bias is necessary to establish a low impedance path for the majority charge carriers (electrons in an NPN transistor) to flow from the base into the collector region. This allows a larger current to flow from the collector to the emitter, known as the collector current.
By biasing the emitter base junction in reverse and the collector base junction in forward, the transistor operates in its active region, where it can amplify small input signals. This biasing condition ensures that the transistor is in a proper operating mode and allows it to function as an amplifier.
If both junctions were forward biased (option D), the transistor would be in saturation mode, where it behaves like a closed switch, conducting a large current between collector and emitter. This is not suitable for amplifier operation.
Similarly, if both junctions were reverse biased (option C), the transistor would be in cutoff mode, where it behaves like an open switch, allowing no current flow between collector and emitter. Again, this is not suitable for amplifier operation.
Therefore, option A) the emitter base junction must be reverse biased, and the collector base junction must be forward biased, is the correct bias condition for the normal operation of a transistor amplifier.