Capacitors and Capacitance, Combination of Capacitors in Series and Parallel

A parallel plate capacitor filled with air has an area of 6 cm² and plate separation of 3 mm. Calculate its capacitance.

A metal foil of negligible thickness is introduced between two plates of a capacitor at the centre. The capacitance of the capacitor will be ______  

Capacitance (in F) of a spherical conductor of radius 1m is ______ 

You are given a number of capacitors labelled as 8μF - 250V. Find the number of capacitors needed to get an arrangement equivalent to 16μF - 1000V. 

The capacity of a parallel plate capacitor is 10 μF when the distance between its plates is 9 cm. What will be its capacity if the distance between the plates is reduced by 6 cm.

Two capacitors each of capacity 2 μF are connected in parallel. This system is connected in series with the third capacitor of 12μF capacity. Find the equivalent capacity of the system.  

Obtain an expression for the energy stored in a charged condenser. Express it in different forms. 

Find the equivalent capacitance between P and Q in the following diagram. The area of each plate is A and the separation between plates is d.