an infinite bus bar may be treated like a m/c with large
amount of inertia, so that the frequency will not change.
and the voltage and frequency remains unchanged regardless
of the equipment connected to it.
In 110V DC supply,if a closed circuit gets open, How can we
identify the voltage which is measured after the
resistor(4KOhm) which is open with negative.it shows 55V +ve
when measured, also the actual positive source is 55V +ve
.Because there is no voltage drop in open circuit. How can
we identify whether this is the voltage which is series with
the resistor or the DC source direct +ve.