Let current `i` flow in the loop having `oo-by` long sides. Consider a segment of width dx at a distance x as shown flux through the regent.
`dphi=[(mu_(0)i)/(2pix)-(mu_(0)i)/(2pi(x+a))]bdximplies phi=int_(c)^(c+b)[(mu_(0)i)/(2pix)-(mu_(0)i)/(2pi(x+a))]bdx=(mu_(0)ib)/(2pi)[ln""(c+b)/(c)-ln""(a+b+c)/(a+c)]`
