Q.With circuit diagram explain the working of CE amplifier.

In a common-emitter amplifier the emitter is common to input and output; the signal is applied to the base and the amplified output is taken from the collector, with a 180° phase shift between them. …

[!TLDR]

A common-emitter amplifier applies the signal to the base and takes the output from the collector; a small base-current change produces a $\beta$-times larger collector-current change, giving a large output voltage that is 180° out of phase with the input.

Circuit: an npn transistor with the emitter common to input and output. Voltage-divider resistors $R_1$ and $R_2$ set the base bias, $R_C$ is the collector load, and $R_E$ with bypass capacitor $C_E$ provides bias stabilisation. The base-emitter junction is forward biased and the collector-base junction reverse biased (active region). The signal is coupled to the base through $C_1$ and the output taken from the collector through $C_2$. …