When a capacitor is connected to a battery, current starts flowing in a circuit which charges the capacitor until the voltage between plates becomes equal to the voltage of the battery. Since between plates of a capacitor there is an insulator/dielectric, how is it possible that current flows in a circuit with a capacitor since according to Ohm's law, current is inversely proportional to resistance and an insulator by definition has a big resistance, so we basically have an open circuit?
how is it possible that current flows in a circuit with capacitor since according to Ohm's law current is inversely proportional to resistance and insulator by definition has a big resistance, so we basically have an open circuit?
The short answer is because electrons can flow to and from a capacitor without the electrons having to pass through the insulation between the plates. The following qualitative explanation is offered:
Assuming the capacitor is not initially charged, then before it is connected to the battery each metal plate has an equal amount of protons (positive charge) and highly mobile electrons (negative charge) so that each plate is electrically neutral and there is no voltage (potential difference) between the plates.
When the capacitor is connected to a battery, the positive terminal of the battery attracts electrons off of the plate connected to it moving them to the positive terminal of the battery. This leaves a deficit of electrons on that plate making it positively charged.
Simultaneously, the negative terminal of the battery supplies an equal amount of electrons to the plate connected to it giving it a surplus of electrons making the plate negatively charged.
This moving of electrons from one plate to the positive terminal battery and from the negative terminal of the battery to the other plate is the capacitor current. Note that the electrons do not travel through the insulating material (dielectric) between the plates.
You can think of it roughly in terms of the electrons being "pulled" off one plate and "pushed" on to the other by the force of the electric field produced by the battery, but that the charges get "stuck" on the plates because they can't get past the insulating dielectric.
Eventually, as you already appear to know, the battery stops moving electrons between the plates when the potential difference across the plates equals that of the battery.