Equivalent capacitance, circular arrangement

[gneill]

batteries/voltage source has resistance,right?

Not ideal ones. An ideal battery would be a pure voltage source, no resistance. Ideal components are perfect representations of the quality that they are specified to be. An ideal capacitor is capacitance only. An ideal inductor is inductance only. An ideal resistor is resistance only. An ideal voltage source is a voltage source only.

Real world components, being made of imperfect real-world materials, will exhibit some mix of traits in addition to the one they are designed for. So a real capacitor, for instance, may have some very tiny resistance and inductance associated with its wire leads. Usually these imperfections are small enough to ignore for practical design and operational purposes. When they are not negligible for a given component or circuit situation you will be told so in the problem statement.

 

[Herman Trivilino]

In such cases we should not apply voltage ?As we can see you did not apply voltage but made A and B connection terminals there when the question asked to find equivalent potential between A and B

To find a voltage or potential difference you would connect a voltmeter.

To apply a voltage or potential difference you would connect a battery.