$A$ transistor works as an amplifier when

The base current in a transistor circuit changes from $45 \mu A$ to $140 \mu A$. Accordingly, the collector current changes from $0.2 \text{ mA}$ to $4.0 \text{ mA}$. The gain in current is

The part of a transistor which is heavily doped to produce a large number of majority carriers is

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.

In the circuit shown, the value of $\beta$ of the transistor is $48$. If the base current supplied is $200 \mu A$, what is the voltage at the terminal $Y$ (in $V$)?

An oscillator is nothing but an amplifier with