According to Ampere's Ciruital Law:
Now consider two straight wires, each carrying current I
, one of infinite length and another of finite length l
. If you need to find out magnetic field because of each, at a point (X) whose perpendicular distance from wire is d
.
You get magnetic field as $\frac{\mu I}{2 \pi d}$. Same for both.
But,
Magnetic field due to infinitely long wire is : $\frac{\mu I}{2 \pi d}$
Magnetic field due to wire of finite length l
: $\frac{\mu I (\sin(P)+\sin(Q)) }{2 \pi d}$, where P & Q are the angles subtended at the point by the ends of the wire.
Why are we getting wrong value for using Ampere's circuit law?