The circuit in Figure 17.93 consists of a battery and a Nichrome wire, through which runs a current $I$.
(a) At the location marked $\times$ (the center of the semicircle), what is the direction of the magnetic field? (b) At the location marked $\times(\text { the center of the semicircle }),$ what is the magnitude of the magnetic field? If you have to make any approximations, state what they are.