Answer
(a) At point A, the magnitude of the magnetic field is greater.
(b) $13\mu T;2.1\mu T$
Work Step by Step
(a) We know that the magnitude of the fields due to each wire are the same at each point, but their directions are opposite at B; therefore, the magnitude of the net magnetic field is greatest at point A.
(b) We know that
$B_A=\frac{\mu _{\circ}}{2\pi r}(I_1+I_2)$
$\implies B_A=\frac{4\pi \times 10^{-7}}{2\pi \times 0.16m}(6.2A+4.5A)$
$B_A=13\mu T$
Now, the magnitude of the magnetic field at point B is given as
$B_B=\frac{\mu_{\circ}}{2\pi r}(I_1-I_2)$
$\implies B_B=\frac{4\pi\times 10^{-7}}{2\pi \times 0.16m}(6.2A-4.5A)$
$\implies B_B=2.1\mu T$
