Question

mention the methods to increase the capacitance of a parallel plate capacitor

Answer 1

Dear student,
Parallel plate capacitor has capacitance
C = ϵ₀A/d
where symbols have their usual meanings.
It can be seen from the above formula that increasing A or decreasing d would increase the C.
Another way is to fill the capacitor with some dielectric material, and if the dielectric material has relative permittivity 'k' then the new capacitance would be 'k' times more than the old one.

Regards