Correct Answer - B
`ABCDE` is equivalent to straight lentght `lambda`
(1) `e=0`
(3) `vec(v)=vhatk` , `vec(B)=Bhati` , `vec(l)=lambdahatj`
`e=Bvlambda`
(4) `vec(v)=vhati , hatl=lambdahatj , vec(B)=Bhatk`
`e=Bvlambda`
(3)
Magnetic field at distance `x` due to long wire
`B=(mu_(0)i)/(2pix),ox`
`de=Bvdx`
`e=(mu_(0)iv)/(2pi)int _(a)^(a+L)(dx)/(x)=(mu_(0)iv)/(2pi)|1nx|_(a)^(a+L)`
`=(mu_(0)iv)/(2pi)1n((a+L)/(a))`
`=(mu_(0)iv)/(2pi)1n(1+(L)/(a)) V_(A)-V_(B)=e`