In a `PN` -junction diode

Options

A. The current in the reverse biased condition is generally very small
B. The current in the reverse biased condition is small but the forwards biased current is independent of the biase voltage
C. The reverse biased current is srongly dependent on the applied biase voltage.
D. The forward biased current is very small in comparision to reverse biased current.

Explanation

To analyze the behavior of a PN-junction diode under forward and reverse bias conditions, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding the PN-Junction Diode**:
- A PN-junction diode consists of two types of semiconductor materials: p-type (which has an abundance of holes) and n-type (which has an abundance of electrons). The junction between these two materials is where the behavior of the diode is defined.

2. **Formation of the Depletion Layer**:
- When the p-type and n-type materials are joined, electrons from the n-side recombine with holes from the p-side, creating a depletion region. This region is devoid of charge carriers and acts as an insulator.

3. **Forward Bias Condition**:
- In forward bias, the positive terminal of the battery is connected to the p-side and the negative terminal to the n-side. This reduces the potential barrier at the junction.
- As a result, holes from the p-side and electrons from the n-side are pushed towards the junction, allowing current to flow. The depletion layer width decreases, and the current increases significantly after a certain threshold voltage (the forward voltage drop).

4. **Reverse Bias Condition**:
- In reverse bias, the positive terminal of the battery is connected to the n-side and the negative terminal to the p-side. This increases the potential barrier at the junction.
- The depletion layer widens, and very few charge carriers can cross the junction, resulting in a very small reverse current. This current remains low until a breakdown voltage is reached, at which point the diode can conduct a large current.

5. **Current Characteristics**:
- In forward bias, the current increases with applied voltage after the threshold is reached.
- In reverse bias, the current is typically very small until breakdown occurs, at which point it can increase dramatically.

6. **Conclusion**:
- The behavior of the PN-junction diode under forward and reverse bias conditions shows that the current in reverse bias is generally very small due to the increased resistance from the widened depletion layer.

### Summary:
- **Forward Bias**: Current flows easily after a threshold voltage due to reduced resistance.
- **Reverse Bias**: Current is very small until breakdown voltage is reached due to increased resistance.