Question

An AC source is connected to a capacitor. Will the rms current increase, decrease or remain constant if a dielectric slab is inserted into the capacitor?

Answer 1

The reactance of a capacitor is given by,
$X_c=\frac{1}{\omega C}$
Also,
$C=\frac{K{\epsilon }_{0}A}{d}$,
where C = capacitance
K = dielectric constant
A = area of plates
d = distance between the plates.
$K>1$
$\therefore$ The capacitance C of the capacitor will increase on inserting the dielectric slab and, consequently, the reactance X_c will decrease.
Rms current, $i_{rms}=\frac{{\epsilon }_0}{\sqrt{2}{X}_C}$

Therefore, rms current will decrease.