1. Capacitance of a system is a measure of the its capacity to hold charge for a given potential difference.
2. Capacitance can be defined as
3. Capacitance is defined even if a capacitor is neutral.
4. SI unit of capacitance is Farad (F).
5. 1F = 1 C V – 1 = 9 x 1011 stat farad.
6. Farad is a too big unit. Practical capacitors are of the order of mF, nF & pF etc.
7. Generally the two plates have equal and opposite charges. Even if, we give different charges to the plates then the inner surfaces facing each other posses equal and opposite charges.
8. The plates are separated by a distance much smaller than dimensions of a capacitor.