Question

why is a current source in parallel and voltage source in series?

Answer 1

um, you mean to increase the current you put them in parallel and to increase voltage you put them in series?

Answer 2

in all the circuit digs i have encountered an independent current source is always in parallel..why?

Answer 3

There's no reason why it must be that way but there are some reasons why it is most likely that way.

The most important reason comes from thevenin's (and norton's) theorems that state that any linear circuit connected to a port can be replaced by a voltage source in series with a resistance or an equivalent current source in parallel with a resistance. So in practical circuits, real linear devices are modelled by one of these two circuit arrangements. One example is the hybrid-pi model of the BJT transistor in active mode which has the collector/emitter current characteristic modelled by a current source in parallel with an output resistance.

Answer 4

real voltage sources and real current sources act that way.