In a CE amplifier, the input ac signal to be amplified is applied across,
A) Forward biased emitter-base junction.
B) Reverse biased collector-base junction
C) Reverse biased emitter-base junction
D) Forward biased collector-base junction

Hint: In a common emitter amplifier the difference between the phases of signal input voltage and signal output voltage, if that is equal to 180 degrees then it is called as phase reversal.

Complete step by step solution:
The common emission amplifier is a three-stage bipolar transistor with a single stage connexion that is used as a power amplifier. In this amplifier the base terminal takes the input while the collector terminal collects the output and the emitter terminal is normal for all the terminals.
The low voltage amplifiers are actually the common emitter amplifiers. These amplifiers have their application in the RF circuits. In general, these amplifiers are used in the Low noise amplifiers

The current gain of the typical emission intensifier is defined as the change ratio between the collection current and the change in the basic current. The voltage gain for this amplifier is defined as the product of the current gain and the ratio of the collector output resistance to the base circuit input resistance.
The input is applied to the base while the output is taken from the collector. The common terminal for both the base and the collector circuits is the emitter.

Input is the basis amplifier junction for a CE amplifier. Therefore, the incoming ac signal is added to the forward biased emitter-base junction.

Note: The standard emitter device is common because it is ideal for the amplification of voltage, especially at low frequencies. In radio frequency transceiver circuits, the widely used amplifiers are still used. Popular setup for emitters typically used for amplifiers of low noise.