Before contact:

Q = Q₁+Q₂

    = V₁C₁+V₂C₂

In contact or after contact

Q₁¹ = C₁V

Q₂¹ = C₂V

And

7) Energy loss in redistribution of charge:

1)      If V₁ = V₂, means two conductors have the same potential then energy loss is zero otherwise

2)      V₁>V₂ or V₂>V₁; DE will always be time positive. Hence, there will be loss of energy in the form of heat.

8) Capacitor (Parallel plate capacitor):

It consist of two plates placed close together and is insulated from one another by air or same dielectric medium. One of the plates is given a charge and other is grounded. This device can store charge or electrical energy.

9) Different types of grouping of capacitors and the effective capacitance:

1) Series Combination:

                                                         Fig (3)

Remember

V = V₁ + V₂ + V₃ + --------------

2) Parallel Combination:

                                                  Fig (4)

Remember:

Q = Q₁ + Q₂ + Q₃ + -----------------

C = C₁ + C₂ + C₃ + -----------------

10) If n parallel plates are connected as shown in the figure below and C¹ is the capacitance between two adjacent plates then total capacitance will be C

C = (n-1) C¹.

   Fig (5)