The elements which may be considered for an ideal inductor as a solenoid,
(A) which is made of a thick wire
(B) which has negligible resistance
(C) which has a sufficiently large inductance
(D) which is made of a thin wire
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (B) and (C) only
An ideal inductor is a pure inductance: it has a large inductance and no resistance, so it stores energy in its magnetic field and dissipates none as heat.
(A) which is made of a thick wire — Correct. Resistance is \( R = \rho l/A \); a thick wire has a large area of cross-section and so a low resistance.
(B) which has negligible resistance — Correct. Any resistance in the coil wastes energy as heat and makes the inductor non-ideal.
(C) which has a sufficiently large inductance — Correct. The solenoid must have enough turns per unit length and area to give a large \( L \), so that its inductive effect dominates.
(D) which is made of a thin wire — Incorrect. A thin wire has a small area of cross-section and a larger resistance, which is the opposite of what an ideal inductor needs.