Diodes Characteristics And Applications

Step 1: Understanding the Behavior of a Diode
- A diode typically has a non-linear characteristic.
- For negative voltage (reverse bias), the current is close to zero until the diode reaches the breakdown voltage.
- For positive voltage (forward bias), the current increases rapidly after the threshold voltage (usually around 0.7 V for silicon diodes).
Step 2: Diode-Resistor Parallel Circuit
In a parallel circuit with a resistor and a diode, the current-voltage characteristic will be influenced by both components:
1. The resistor will cause a linear increase in current with voltage.
2. The diode will show a non-linear characteristic, initially having very small current, but rapidly increasing as the forward voltage crosses a threshold.
Step 3: Analyzing the Graphs
- Option (A): A smooth curve rising steeply for positive voltage matches the typical behavior of a diode, but the curve might be too idealized for a parallel resistor.
- Option (B): A straight line is not correct because a diode does not have a linear characteristic.
- Option (C): A graph with a small hump suggests a more complex interaction, which could happen in a more complicated circuit setup but is less common for a simple parallel diode-resistor setup.
- Option (D): A sharply increasing graph after a certain voltage threshold is the most likely behavior for the diode, especially after the threshold voltage is crossed.
Step 4: Conclusion The most probable current-voltage characteristic for a diode connected in parallel with a resistor is represented by a graph that starts with a very small current and sharply increases after a certain voltage threshold is crossed.
Thus, the correct answer is:

Concept:
Parallel combination:
- Resistor gives linear I–V relation.
- Diode gives exponential current in forward bias.

Step 1: Forward bias (positive V)
Diode conducts strongly ⇒ exponential rise.

Step 2: Reverse bias (negative V)
Diode blocks current ⇒ only resistor conducts ⇒ linear I–V.

Step 3: Resulting graph
- Linear in negative region
- Exponential in positive region
Matches option (B).