The reactance of a capacitor is given by,Xc​=ωC1​ Also,C=dKε0​A​ where Cˉ= capacitanceK= dielectric constantA= area of platesd= distance between the plates.K>1 ∴ The capacitance C of the capacitor will increase on inserting the dielectric slab and, consequently, the reactance Xc​ will decrease.Rms current, irms​=2​XC​ε0​​ Therefore, rms current will decrease.