Source of electrical energy

The source of electrical energy are classified into two group :

1. Voltage source
2. Current source

These sources are further classified into two types as:

1. Ideal sources
2. Practical source

Voltage source

Ideal Voltage Source

An ideal voltages sources are defined as the voltage source which provides a constant terminal voltage across the load for any variation of load current lL or load resistances R.

Practical Voltage Source

It is not possible to get the ideal voltage source producing a strictly constant voltage across its terminals while supplying the current.

Voltage source in series

The two practical voltage sources in series can be combined together to get a single equivalent voltage source.

Voltage sources in parallel

For parallel combinations of two ideal sources, their voltages must be same with the same polarities as V1 =V2

Current sources

Ideal current sources

An ideal current source is defined as the current source which provides a constant current through the load for any variation of load voltage VL or loads resistance RL.

Practical current Practical

Practically it is impossible to visualize the ideal current source supplying a strictly constant current through the load across terminals a and B.

Current sources series

For series combinations of two ideal current sources, their current must be the same in magnitude and directions.

I1 = I2
practical current sources

The two practical current sources in parallel can be combined together to get a single equivalent current source.