Diode
- A diode only allows current to flow in one direction.
- It has very high resistance in the reverse direction.
I-V characteristic of a diode
In the forward direction:
- The current is incredibly small until it reaches its activation voltage.
- That’s usually about 0.7 V for a silicon diode.
- After that, the current increases mostly proportionally with voltage. In the reverse direction:
- The current is almost zero, regardless of the voltage.
- This means the resistance is extremely high in the reverse direction.
Uses of diodes
- Diodes can be used to convert alternating current (AC) to direct current (DC).
- This is done in a component called a rectifier.
- The diode only allows the positive half-cycles of the AC to pass through.
- The negative half-cycles are blocked, resulting in a pulsating DC output.
flashcards
| Question | Answer |
|---|---|
| What is the primary function of a diode? | It only allows current to flow in one direction and has very high resistance in the reverse direction. |
| Describe the I-V characteristic of a silicon diode in the forward direction. | The current is incredibly small until it reaches the activation voltage (about 0.7 V). After that, the current increases mostly proportionally with voltage. |
| What is the activation voltage for a typical silicon diode? | About 0.7 V. |
| Describe the I-V characteristic of a diode in the reverse direction. | The current is almost zero, regardless of the voltage, meaning the resistance is extremely high. |
| How is the I-V characteristic of a diode used to convert AC to DC? | The diode acts as a rectifier, allowing only the positive half-cycles of AC to pass through and blocking the negative half-cycles, producing a pulsating DC output. |
| What is the component called that uses a diode to convert AC to DC? | A rectifier. |
| What happens to the negative half-cycles of an AC current when passed through a diode rectifier? | They are blocked, resulting in a pulsating DC output. |