Question

A short solenoid of radius $a$, number of turns per unit length $n_{1}$ and length $L$ is kept coaxially inside a very long solenoid of radius $b$, number of turns per unit length $n_{2}$. What is the mutual inductance of the system?

• A. $\mu_{0} \,\pi \,b^{2} \,n_{1} \,n_{2} \,L$
• B. $\mu_{0}\, \pi \,a^{2} \,n_{1}\, n_{2}\, L^{2}$
• C. $\mu_{0} \,\pi \,a^{2} \,n_{1}\, n_{2}\, L$
• D. $\mu_{0}\, \pi\, b^{2} \,n_{1}\, n_{2}\, L^{2}$

Answer 1

Answer: (C)

The mutual of the system $M=\mu_{0} \,n_{1} \,n_{2} \,\pi\, a^{2}\, L$