question_answer

Direction: Q.26 to Q.30

Mutual inductance is the phenomenon of inducing emf in a coil, due to a charge of current in the neighbouring coil. The amount of mutual inductance that links one coil to another depends very much on the relative positioning of the two coils, their geometry and relative separation between them. Mutual inductance between the two coils increases \[{{\mu }_{r}}\] times if the coils are wound over an iron core of relative permeability\[{{\mu }_{r}}\].

Read the above passage carefully and give the answer of the following questions:

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) \[{{\mu }_{0}}\pi {{b}^{2}}{{n}_{1}}{{n}_{2}}{{L}^{2}}\]