Is there any kind of material that when inserted between the plates of a capacitor reduces its capacitance.?

Does the capacitance of a capacitor depend upon its shape?

A sheet of aluminium foil of negligible thickness is introduced between the plates of a capacitor. The capacitence of the capacitor.

A parallel plate capacitor of plate area A and plate separation d is charged to potential difference V and then the battery is disconnected. A slab of dielectric constant K is then inserted between the plates of the capacitor so as to fill the space between the plates. If Q, E and W denote respectively, the magnitude of charge on each plate, the electric field between the plates (after the slab is inserted), and work done on the system, in question, in the process of inserting the slab,

A very very thin sheet of aluminium is placed in between the plates of the capacitor, the capacitance will

For a given potential difference, does a capacitor store more or less charge with a dielectric than it does without a dielectric constant (K) is inserted between the two plates of capacitor. What is the new of charge stored in the capacitor?

Explain why the capacitance of capacitor increases when dielectri slab is inserted between the plates of the capacitor. Derive an expression for energy stored in a charged capacitor.

If a parallel plate capacitor of capacitance C is kept connected to a supply voltage V and then to just fill the space, dielectric slab is inserted between the plates. What will be the change in the capacitance the charge, the potential difference, the electric field and the energy stored?

Show that in parallel plate capacitor, if the medium between the plates of the capacitor is filled with insultaing substance of dielectric contant k, its capacitance increases.