Assertion (A): In imperfect capacitors, the current does not lead the applied ac voltage by 90°.
Reason (R): When subjected to ac fields, the dielectric constant can be expressed as ∈'r - j∈"r.
Answer: A
Imaginary part of ∈r gives rise to absorption of energy by the material from alternating field.
Hence current does not lead the voltage by 90°.