The potential difference across a diode is the voltage required for the diode to conduct current in the forward direction.
Explanation
A diode allows current to flow mainly in one direction (forward bias). To start conduction, a minimum voltage - called the threshold voltage or cut-in voltage - is required.
Typical Values
- Silicon diode → approximately 0.7 V
- Germanium diode → approximately 0.3 V
Behavior of a Diode
1. Forward Bias
- When the diode is connected correctly (positive to anode, negative to cathode)
- Current flows after reaching threshold voltage
2. Reverse Bias
- When connected in opposite direction
- Very little or no current flows
- Acts like an open circuit
Graph Insight
- Below threshold → almost no current
- After threshold → current increases rapidly
Practical Applications
- Rectifiers (AC to DC conversion)
- Electronic circuits
- Signal processing
Summary
The potential difference across a diode is the minimum voltage needed to allow current flow, typically 0.7 V for silicon and 0.3 V for germanium.