Q. Coefficient of coupling between two coils of self-inductances $L_{1}\ and\ L_{2}$ is unity. It means
A) 50% flux of $L_{1}\ is\ $linked with $L_{2}$
B) 100% flux of $L_{1}$is linked with $L_{2}$
C) $\sqrt{L_{1}}$ time of flux of $L_{1}$ is linked with $L_{2}$
D) None of the above
Explanation
(b) Two coils are said to be magnetically coupled if full or a part of the flux produced by one links with the other. Let $L_{1}\ and\ L_{2}$be the self- inductances of the coils and $M$ be their mutual inductances, then
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ k = \frac{M}{\sqrt{L_{1}L_{2}}}$
When 100% flux produced by one coil links with the other, then mutual inductance between the two is maximum and is given by
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ M = \sqrt{L_{1}L_{2}}$
In that case, $k = 1(unity)$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.