Animesh said:

Thanks to all for that nice discussion.

I still remember those primary classes, where I studied that voltage

difference is necessary to make the current flow in the circuit.

Current source consists only current so how they are able to make the

current flow?

Current (and voltage) sources are theoretical devices.

A voltage source will produce its 'rated' voltage across either an open

circuit, which isn't a big deal. Or it will produce its rated voltage

across a zero ohm conductor, which is impossible in the practical world,

since that results in an infinite current.

Likewise, a current source will produce a current through an impedance,

including an open circuit. This will result in an infinite voltage.

In real life, each of these sources is incorporated into a circuit model

with the appropriate series (for a voltage source) or shunt (for a

current source) impedance, which gives the model a behavior that

approximates a real world circuit.

On the other hand, there are no real world circuits that behave exactly

as a pure current or voltage source.

Or the voltage drop first occurs across parallel Thevenin Resistance

(in Norton Equivalent) which facilitates the current flow.

The purpose of the Thevenin and Norton equivalent circuits is only to

analyze their behavior at the circuit terminals. You can calculate what

might be going on inside each circuit, but that isn't necessary and

doesn't correspond to anything that would occur in real hardware.

All seems to be silly & confusing!

Just wait until you whip out the old Simpson multimeter and try to

measure an imaginary voltage. ;-)