Assertion (A): In a perfect capacitor, the current density is given by ω ∈0E0∈'rcos(ωt + 90°), where ∈r' is real part of dielectric constant.
Reason (R): In a perfect capacitor, dielectric losses are zero.
Answer: A
If dielectric losses are zero, the current in capacitor leads the applied voltage by 90°.
Also imaginary part of is ∈r is zero.