Calculate the inductance of a unit length of a double tape line as shows in Fig if the tapes are separated by a distance `h` which is considerably less than their width `b`.

Options

A. `(mu_(0)h)/(b)`
B. `(mu_(0)h)/(2b)`
C. `(2mu_(0)h)/(b)`
D. `(sqrt(2)mu_(0)h)/(b)`

Answer

A

Explanation

`oint vec(B)*dvec(l) = mu_(0)I rArr B2b = mu_(0)I`
`rArr B = (mu_(0)I)/(2b) rarr` due to one tabe
Net field `= 2B`


Magnetic flux passing through this double tabe
`phi = 2BA = 2B (l//h) rArr phi = (mu_(0)I)/(b) lh`
`L = (phi)/(I) = (mu_(0)lh)/(b) rArr (L)/(l) = (mu_(0)h)/(b)`