I need help with two questions: 2. A capacitor filled by a dielectric slab (K=4.6) is connected to a 12.0-V battery and charged up. The capacitor is then disconnected from the battery and the slab is removed. Find the amount by which the potential difference across the plates changes. Specify whether the change is an increase or a decrease. 3. A certain capacitor has a potential difference Vo between its two plates. When this values is increased by 3.25 V, the charge on each plate increases in magnitude by 13.5 uC. Determine the capacitor’s capacitance.
for questions 2 I used q=(epsilon*K*A/d)*V, and stated that the charge will remain constant to get K1V1=K2V2 to get the potential difference to be 57.6V so a change of 45.6V which is an increase. Did I solve this problem correctly? And I have no idea on how to do 3