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. ;-)