Question

An air capacitor is charges to a certain potential difference. It is then immersed in oil. What happens to its (a) capacitance (b) charge (c) potential.

Answer 1

C=q/V
dielectric constant will increase, as C is directly proportional to dielectric constant, so C will increase.
as most oils are insulators so no flow of charge takes place therefore q remains the same but voltage decreases.