# Dependent or independent sources of voltage and current

I am confused with this term of dependent and independent . What exactly this mean .does dependent sources mean that if we connect a dependent source of voltage and current in same circuit ,they will interfere with each other value. But how can this happen? Is there any example of such kind of sources ? And does they follow ohms law?

## 1 Answer

A fixed or independent voltage or current source is one that provides a constant output. A battery is an example of an approximation to a fixed voltage source.

A dependent voltage or current source is one that provides an output that's a scaled version of an input. The drain of a FET is an example of an approximation to a voltage dependent current source, the output being $g_m$ times the gate voltage.

The outputs of a number of these things in a network will interfere or not depending on what type of source they are, not whether they are dependent or independent. For instance, two voltage sources in parallel do not play nice, and a simulator will refuse to simulate them, similarly current sources in series.

A current source in parallel with a voltage source does work well, the voltage source defines the voltage the current source works into, the current source defines the current drawn from the voltage source.

We never encounter pure voltage or current sources in practice, but we can find or make things that are good approximations to them, over a defined range.