A lamp is connected in series with a capacitor. Predict your observations for dc and ac connections. What happens in each case if the capacitance of the capacitor is reduced?

In case of dc, the frequency is zero, so the capacitive reactance is infinite, hence there will no flow of current in the circuit and the lamp will not glow. If the capacitance of the capacitor is reduced, there will be no change in the circuit which makes the lamp to remain in similar position.

In case of ac, the capacitors give finite reactance which allows the current to flow making the lamp to glow. When capacitance C of the capacitor gets reduced, there will be an increase in the reactance which leads to decrease in circuit current making the lamp to glow dim.