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 = 1/(omegaC)`
Also,
C = `(K_{ε0}A)/d`
where C = capacitance
K = dielectric constant
A = area of plates
d = distance between the plates.
K>1
∴ 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 = ε_0/sqrt(2X_c`
Therefore, the rms current will increases.