CBSE Class 12-science Answered

The main purpose of using a capacitor in a circuit to store electrical potential energy in the form of charge. So whenever a capacitor get charged it consume electricity and charge is flowing towards the plate of capacitor and in this case if a galvanometer is placed in series then it will show the deflection. When the capacitor gets fully charged its stops consuming electricity so current in the circuit will become zero. When a capacitor is being discharged charges starts to flow again and this result in the current and due to this current a deflection can be observed in galvanometer. 

This particular current between the plates is known as displacement current. Modifications in ampere law can be find in any book. What it does is its start to take account of electric flux changes by this displacement current.