Question

An infinitely long wire of uniform cross section carries a current whose current density varies as `j=br^(alpha)`. Where `b=(10^(7))/(pi)`unit,` alpha=.1`unit and `r` the distance from axis. The magnetic induction at a distance `0.25` from axis is given by `(nxx5)/(3)x10^(-2)` tesla. Find `n`

Answer 1

Correct Answer - 5
`I=int(2pix)dx=int_(0)^(r)bx^(alpha)2pixdx=(2pibr^(a+2))/(a+2)`
`ointB2pir=mu_(0)(2pibr^(a+2))/(alpha+2)=(mu_(0)br^(a+1))/(alpha+2)impliesn=5`