Figure shows two concentric loops of radii R and r (R gtgt r). A current `i` is passed through the outer loop. Find the flux linked with inner loop and the mutual inductance of the arrangement.

Explanation

At O, B `(mu_(0)i)/(2R)`. As R gtgt r,
`therefore" "` We can asscume that same field B acts
on the total area of inner loop.
`phi=BxxA`
`rArr phi=(mu_(0)i)/(2R)xx pir^(2)`
`M=(phi)/(i)=(mu_(0)r^(2))/(2R)`