A series R-C circuit is connected to an alternating voltage

A series R-C circuit is connected to an alternating voltage source. Consider two situations:
(A)When capacitor is air filled.
(B)When capacitor is mica filled.
Current through resistor is i and voltage across capacitor is V then :

For series R – C circuit, capacitive reactance,
Z_c = √R² + (1 / Cω)²

current i =	V	=	V
	Z_c		√R² + (1/Cω)²

V_c = iX_c =	V	×	1
	√ R² + (1 / Cω)²		(1/Cω)

V_c = V / √(R Cω)² + 1
If we fill a di-electric material like mica instead of air then capacitance C↑ ⇒ Vc↓ So, V_a > V_b