A p-n junction diode \((D)\) shown in the figure below can act as a rectifier. An alternating current source \((V)\) is connected in the circuit. The current \((I)\) in the resistor \((R)\) can be shown by which graph?
Show Hint
A single diode produces a half-wave rectified output:
\[
\text{Positive half-cycle} \rightarrow \text{Current flows}
\]
\[
\text{Negative half-cycle} \rightarrow \text{No current}
\]
A full-wave rectifier requires two diodes with a centre-tapped transformer or four diodes in a bridge rectifier.
Concept:
A single p-n junction diode in series with a resistor acts as a half-wave rectifier.
• During the positive half-cycle, the diode is forward biased and current flows.
• During the negative half-cycle, the diode is reverse biased and current does not flow.
Therefore, only one half of the AC signal appears across the load resistor.
Step 1: Analyse the positive half-cycle.
When the input voltage is positive,
\[
\text{Diode is forward biased}
\]
Hence,
\[
I \neq 0
\]
and current flows through the resistor.
Step 2: Analyse the negative half-cycle.
When the input voltage is negative,
\[
\text{Diode is reverse biased}
\]
Hence,
\[
I=0
\]
and no current flows through the resistor.
Step 3: Identify the output waveform.
The output current consists of only positive half-cycles separated by intervals of zero current.
This corresponds to a half-wave rectified output.
\[
\boxed{
\text{Current flows only during alternate half-cycles.}
}
\]
Step 4: State the answer.
The correct graph is
\[
\boxed{\text{Graph 2}}
\]
Hence, the correct option is
\[
\boxed{(B)}
\]
