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

Given below are two statements:
Statement $I$: Photovoltaic devices can convert optical radiation into electricity.
Statement $II$: Zener diode is designed to operate under reverse bias in the breakdown region.
In the light of the above statements,choose the most appropriate answer from the options given below:

The $I-V$ characteristic of an $LED$ is:

Consider the following statements:
Statement $(A)$: The resistance of an ideal diode in forward biased condition is zero.
Statement $(B)$: In a half-wave rectifier,the load current flows only for every half cycle of the input signals.
Statement $(C)$: In the breakdown region,a Zener diode behaves as a constant voltage source.

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

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 $t$?