Capacitors

Question 1

Capacitance definition

Answer 1

charge stored per unit potential difference

Question 2

Derivation of E=½QV

Answer 2

(delta)W = V (delta)Q explained (1)
energy stored = total work done in charging = charge x average voltage (1)
energy stored = work done (= ½QV) (1)

Question 3

Time constant definition

Answer 3

Time taken for the voltage (or charge or current) to fall to of its initial value.