Find the magnetic field at the point P in figure. The curved portion is a semicircle and the straight wires are long.

Explanation

Solution: The magnetic field at P due to any current
element in the figure is perpendicular to the plane of
the figure and coming out of it. The field due to the
upper straight wire is
B_1 = 1/2 xx ((mu_0)i/2pi (d/2)) = ((mu_0)i/(2 pi d))
Same is the field `B_2` due to the lower straight wire. The
field due to the semicircle of radius (d//2) is
` (B_3)= 1/2 xx ((mu_0)i/2(d/2))= ((mu_0)i/ 2d)`
`The net field is B= (B_1)+(B_2)+(B_3)= ((mu_0)i/2d) [1+(2/pi)].`