Passive components cannot amplify signals or provide power gain: resistors dissipate electrical energy, while capacitors store and release it. Active components use semiconductor behaviour to control current, enabling rectification, switching, or amplification.
How the Components Behave
In an electronic system, components process electrical inputs to produce an intended output. Their functions determine how signals and energy move through a circuit.
| Component | Classification and function | Typical application |
|---|---|---|
| Resistor | Passive: limits current and produces a voltage drop. It dissipates electrical energy as heat. | Protecting an LED or creating a potential divider |
| Capacitor | Passive: stores energy temporarily in an electric field, then releases it. | Smoothing a power supply or producing a time delay |
| Diode | Active semiconductor: allows significant current mainly in one direction. | Rectification, circuit protection, or light emission in an LED |
| Transistor | Active semiconductor: a small input controls a larger current. | Electronic switching or signal amplification |
A resistor follows the relationship . Increasing resistance reduces current for a fixed potential difference . A capacitor stores charge according to , where capacitance measures its ability to store charge.
