Ideal sources are those imaginary electrical sources which provide constant voltage or current to the circuit regardless of the load current. These ideal sources don’t have any internal resistance. Where it is impossible to build a source with zero internal resistance. So, all the real sources are called practical sources.

**Difference between Ideal and Practical Voltage and the Current source is that the output of an imaginary ideal source is independent of the load**.

The electrical sources are those devices which provide active power to a circuit. There is two type of sources available in electrical networks, a voltage source or current source. The purpose of the voltage source is to provide voltage rather than the current and current source is to provide current rather voltage. Each source is then categorized as an ideal or practical source.

## Ideal and practical voltage source:

An imaginary voltage source, which can provide a constant voltage to load ranging from zero to infinity. Such voltage source is having zero internal resistance, $R_{s}$ and is called **Ideal Voltage Source**. Practically it is not possible to build a voltage source with no internal resistance and constant voltage for that long range of the load.

*Practical voltage sources* always have some resistance value in series with an ideal voltage source. And because of that series resistance, voltage drops when current passes through it. So, Practical Voltage Source has internal resistance and slightly variable voltage.

## Ideal and practical current source:

An imaginary current source, which provides a constant current to any load ranging from zero to infinity. Remember that the current provided is independent of voltage. The **ideal current source** is supposed to have infinite internal resistance, $R_{s}$. Again it is not practically possible to make one.

*Practical Current Source* has some internal resistance connected in parallel to Ideal Current Source. And some of the current flow through it and the amount of flow depends upon the load.

## Dependent or Independent Sources:

A voltage source not depending upon other circuit parameters are an independent source. Independent sources provide almost constant voltage/current irrespective of different circuit elements (slightly changed caused by internal resistance).

In case of dependent sources, the output of the source depends upon some circuit parameter. By changing those parameters in circuit output of the source are adjusted. There are four types of dependent sources:

- Voltage-controlled Current Source (VCCS), where the current source is dependent on voltage.
- Current-controlled Current Source (CCCS), where current source is dependent on current.
- Voltage-controlled Voltage Source (VCVS), where the voltage source is dependent on another voltage.
- Current-controlled Voltage Source (CCCS), where voltage source is dependent on current source. \(\)