The voltage gain of the following amplifier is

The time variations of signals $A, B$ and $C$ are shown below. Choose the correct statement.

The box in the circuit below has two inputs marked $V_{+}$ and $V_{-}$ and a single output marked $V_{o}$. The output obeys the following relation:
$V_{o} = \begin{cases} +10 \, V & \text{if } V_{+} > V_{-} \\ -10 \, V & \text{if } V_{+} < V_{-} \end{cases}$
Which of the following graphs represents the output $V_{o}$ as a function of time $t$?

Identify the semiconductor devices whose characteristics are given below,in the order $(a), (b), (c), (d)$.

When a potential difference is applied across,the current passing through:

In which of the following circuits is the junction reverse biased?