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Materials and Components - Engineering

Q1:

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.

A Both A and R are true and R is correct explanation of A

B Both A and R are true but R is not correct explanation of A

C A is true but R is false

D A is false but R is true

ANS:A - Both A and R are true and R is correct explanation of 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°.