Question

In a CE transistor circuit, where is the input AC signal applied?

1) Base
2) Emitter
3) Collector
4) None of the above

Answer 1

The input AC signal in a common emitter transistor circuit is typically applied to the (1) base.

Step-by-step explanation:

In a common emitter (CE) transistor circuit, the input AC signal is typically applied to the base of the transistor. A junction transistor, which is a type of bipolar transistor, has three regions: the emitter, base, and collector. The voltage applied to the base serves as a control mechanism, effectively acting as a valve that allows control of the electric current flowing from the emitter to the collector.

To further explain, when a positive voltage is applied to the base, a small current known as the base current IB flows into the base. This base current then controls a much larger collector current Ic in the collector region. The factor by which the base current is amplified to produce the collector current is known as the current gain (β) of the transistor.

For example, if the base current IB is 4.4 A and the current gain is 1126, the collector current can be calculated using the relationship Ic = β * IB. Therefore, the collector current Ic would be 4.4 A * 1126, which equals 4954.4 A.