Series capacitors are generally employed to imporve the stability of the system and to increase the voltage rating. We know that the reactance of capacitor is given as RC=
1
2
πfc For an AC source, frequency f > 0 ie. RC=
1
2
xfc<0 which means that capacitor offers a constant resistance in A.C. circuit i.e. it allows the lamp to glow continuously. In case of inductance, the brightness of the lamp will depend upon the number of turns in the inductor