# Solved Problems-14

Problem-14

Determine the self-inductance of a coaxial cable of inner radius â€˜

*a*â€™ and outer radius â€˜*b*â€™ when the inner conductor is solid.Solution

Here, we have to find two inductances:

(1) Internal inductance,

(2) External inductance,

(1) Internal inductance,

*L*_{in}, considering the flux linkages due to the inner conductor(2) External inductance,

*L*_{ext}, considering the flux linkages between the inner conductor and the outer conductors**Coaxial cable**

Now, magnetic energy stored in the inductor is,

where

**(a) For 0 â‰¤**

*r*â‰¤*a*:By Ampereâ€™s law,

**(b) For**

*a*â‰¤*r*â‰¤*b*:By Ampereâ€™s law,

Hence, the total inductance of the coaxial cable is,