Q. Three solenoid coils of same dimension, same number of turns and same number of layers of winding are taken. Coil 1 with inductance $L_{1}$ was wound using a Mn wire of resistance 11$\Omega m^{- 1}$;Coil 2 with inductance $L_{2}$ was wound using the similar wire but the direction of winding was reversed in each layer; Coil 3 with inductance $L_{3}$was wound using a superconducting wire. The self-inductance of the Coils $L_{1},\ L_{2},\ L_{3}$ are
A) $L_{1} = \ L_{2} = \ L_{3}$
B) $L_{1}, = L_{2};\ L_{3} = 0$
C) $L_{1}, = L_{3};\ L_{2} = 0$
D) $L_{1} > L_{2} > L_{3}$
Explanation
(c) As inductance $L_{2}$ was wound using the similar wire but the direction of winding is reversed, so flux through $L_{2}$ is zero.
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ L_{2} \propto \phi = 0$
Also, $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ L_{1} = L_{3}$
Therefore, $\ \ \ \ \ \ \ L_{1} = L_{3},\ L_{2} = 0$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.