A very long wire carrying a conventional current of 41 amper

A very long wire carrying a conventional current of 4.1 amperes is straight except for a circular loop of radius 7 cm (see the figure above). Calculate the approximate magnitude and direction of the magnetic field at the center of the loop. Note, In the figure above, the direction) is out of the page, and the direction k is Into the page. B = 2.27 times 10^-4, direction = k B = 9.10 times 10^-5 [T], direction = e B = 2.27 times 10^-4 m. direction = a B = 4.85 times 10^-5[T], direction = i B = 7.32 times 10^-5[T], direction = k

Solution

due to circular part:

B1 = u0 I / 2 R = (4pi x 10^-7 x 4.1) / (2 x 0.07) = 3.68 x 10^-5 T out of page

due to straight wire:

B2 = u0 I / 2 pi R = (4pi x 10^-7 x 4.1) / (2 x pi x 0.07)

B2 = 1.17 x 10^-5 T out of page.

Bnet = B1 + B2 = 4.85 x 10^-5 T out of page

Ans: 4th option