Which region is the least doped in a transistor?

Three amplifiers,each having a voltage gain of $10$,are connected in series. The resultant gain would be

What is the phase difference between the input and output voltage for a common-base amplifier?

The transfer characteristic curve of a transistor,having input and output resistance $100\,\Omega$ and $100\,k\Omega$ respectively,is shown in the figure. The voltage and power gain are respectively:

In $n-p-n$ transistor, in $CE$ configuration:

Consider the circuit arrangement shown in figure $(1)$ for studying input and output characteristics of an $n-p-n$ transistor in $CE$ configuration. Select the values of $R_B$ and $R_C$ for a transistor whose $V_{BE} = 0.7 \, V$, so that the transistor is operating at point $Q$ as shown in the characteristics shown in figure $(2)$. Given that the input impedance of the transistor is very small and $V_{CC} = V_{BB} = 16 \, V$, also find the voltage gain and power gain of the circuit making appropriate assumptions.