An electrical circuit is made up of different elements interconnected through conductors forming a closed path. Depending upon the characteristics and behavior, the circuit components are classified as,- Active and Passive Components
- Linear and Non-linear Components
- Unilateral and Bilateral Components
- Lumped and Distributed Components.
In this article let us learn about active and passive components with examples and major differences between active and passive components.
Difference Between Active and Passive Components :
| Parameter | Active Component | Passive Component |
|---|---|---|
| Definition | The circuit component which can generate electrical energy or can provide amplification to the signal is called Active Component. | The circuit component which consumes electrical energy and stores it or dissipates it in the form of heat is called Passive Component. |
| Control of Current | Active components can control the current flow in the circuit. | Passive components cannot control the current flow in the circuit. |
| Power Gain | Active components have capable of providing power gain. | Passive components cannot provide power gain. |
| Need for External Source | Some active components like transistors and SCRs require some external power for their operation. | Passive components do not require any external power source for their operation. |
| Amplification | Active components can amplify electrical signals i.e., increasing the strength of the signal. | Passive components do not provide any power gain hence they cannot amplify signals. |
| Function | Active components will produce electrical energy. | Passive components absorb electrical energy and store it or convert it into some other form. |
| Slope of VI Curve | The ratio of voltage to current will be negative for active components at any point. | The ratio of voltage to current will be positive for passive components all the time. |
| VI characteristics | The VI characteristics of active components lie in the 2nd and 4th quadrants. | The VI characteristics of passive components lie in the 1st and 3rd quadrants. |
| Examples | Examples of active components are voltage source, current source, battery, alternator or dc generator, transistor, LED, photodiode, etc. | Examples of passive components are resistors, inductors, capacitors, transformers, diodes, etc. |
What is Active Component?
The circuit element which supplies power in the circuit in the form of voltage or current for a very long period is called Active Component. Active components have the capability to generate electrical energy and can control current flow in the circuit. Active components also have the ability to amplify signals or provide power gain.
Some common examples of active components are voltage sources, current sources, generators or alternators, transistors, diodes (photodiodes, tunnel diodes, Gunn diodes), silicon-controlled rectifiers (SCR), etc.
Voltage Source :
A voltage source is a two-terminal device that produces potential difference or voltage as output. A voltage source that delivers constant voltage regardless of the amount of current drawn in the circuit is called Ideal Voltage Source.
An ideal voltage source has zero internal resistance which means a 100% efficient source of voltage. But in practice, it is impossible to have an ideal voltage source. Every voltage source has some internal resistance due to which the voltage delivered will no more remain constant. Examples of voltage sources are batteries, generators, alternators, piezoelectric disks, etc.
Current Source :
The circuit element which produces a specified magnitude of current in the circuit is called Current Source. Similar to an ideal voltage source, an ideal current source delivers constant current independent of load or any other circuit conditions. An ideal current source has infinite internal resistance. Transistor and photovoltaic cells are examples of current sources.
Transistor :
A transistor is a semiconductor device with three terminals emitter, base, and collector. A transistor controls the current or voltage in the circuit. In addition to that transistors can amplify electrical signals. Hence a transistor is considered an active element.
Diode :
Generally, diodes are considered as the passive components, but a diode with negative differential resistance i.e., the current decreases with an increase in applied voltage, has the capability of amplifying an electrical signal. Thus a diode with negative differential resistance like a Tunnel diode and Gunn diode are considered as the active component.
What is Passive Component?
Passive components do not have the capability of independent energy generation or supply of energy like active components. Passive components have the capability to handle energy in the circuit by storing it in the form of a magnetic or electric field or converting it into some other form of energy.
Unlike the energy generation property of active components, passive components absorb energy. Some examples of passive components are resistors, inductors, capacitors, transformers, etc.
Resistor :
A resistor is a two-terminal device that resists the flow of current in the circuit. The resistance of a resistor gives the amount of opposition made to the flow of current. Since no energy is being generated by a resistor it is called Passive Component.
Inductor :
An inductor is basically a coil that stores electrical energy in the form of a magnetic field for a short period of time when current flows through it. Inductors are used to create filter circuits, tunning circuits, control electric spikes, etc. Therefore inductor is termed as a passive component because it consumes and stores electrical energy.
Capacitor :
Similar to an inductor, a capacitor also stores energy but in the form of an electric field. A capacitor accumulates electric charge on two electrodes separated by an insulating material when connected to a source and dissipates its stored energy when disconnected from the source. Thus capacitor is also a passive component.
Transformer :
A transformer is basically two mutually coupled inductors mostly used in power transmission and distribution systems. A transformer is used to step up and step down the voltage in an ac circuit. Since power on the input and output side of the transformer is maintained constant, it is therefore considered as the passive component.