a rectangular loop, as shown in Fig. 3.66, moves away from an infinitely long wire carrying a current `I. Find the emf induced in the rectangualr loop.

Explanation

`E=B_(1)LV-B_(2)LV=(mu_(0)i)/(2pix)Lv-(mu_(0)i)/(2pi(x+b))Lv=(mu_(0)iLbv)/(2pix(x+b))`
Aliter:
Consider a small segment of width `dy` at a distance `y` from the wire.
Let flux through the segment be `dphi`.
`therefore dphi=(mu_(0)i)/(2piy)Ldy`
`therefore phi=(mu_(0)iL)/(2pi)underset(x)overset(x+b)int(dy)/y=(mu_(0)iL)/(2pi)(ln(x+b)-lnx)`
Now `(dphi)/(dt)=(mu_(0)iL)/(2pi)[1/(x+b)(dx)/(dt)-I/x(dx)/(dt)]=(mu_(0)iL)/(2pi)[((-b))/(x(x+b))]v=(-mu_(0)ibLv)/(2pix(x+b))`
`therefore` induced `emf=(-mu_(0)ibLv)/(2pix(x+b))`