Passive component
From Wikipedia, the free encyclopedia
A passive component is an electronic component that does not increase the power of the electrical signal on which it acts. It may actually end up decreasing the power of the signal it is acting upon. As such, a passive component may draw the energy it uses for its own operation directly from the signal on which it is operating.
In contrast, an active component does increase the power of the signal on which it acts. The energy it adds to the signal must be drawn from a power source other than the signal on which it is operating.
Conceptually, a passive component may be thought of as an electrical device which does not need to be "powered". Technically speaking however, since no device is 100% efficient, all devices must "use" some energy during their operation by converting it to heat. With passive components, such energy is drawn from the signal. However, the resulting power reduction is sometimes so slight that it may be considered negligible for most purposes.
[edit] Examples
- Resistors increase the current at the expense of the voltage.
- Capacitors store electrical energy.
- Diodes control the current's direction.
- Inductors convert alternating electrical currents into alternating magnetic fields.
[edit] Applications
- The classic crystal radio receiver, an AM radio receiver that does not require any electricity, is made entirely from passive components.
- A passive filter is an electronic filter made entirely from passive components.
