In Fig. 29-44 point ${\mathit{P}}_{\mathbf{1}}$ is at distance $\mathit{R}\mathbf{=}\mathbf{}\mathbf{13}\mathbf{.}\mathbf{1}\mathbf{}\mathbf{\text{cm}}\mathbf{}$ on the perpendicular bisector of a straight wire of length $\mathit{L}\mathbf{=}\mathbf{}\mathbf{18}\mathbf{.}\mathbf{0}\mathbf{}\mathbf{\text{cm}}$. carrying current. (Note that the wire is not long.) What is the magnitude of the magnetic field at ${\mathit{P}}_{\mathbf{1}}$ due to i?

In Figure 29-46 two concentric circular loops of wire carrying current in the same direction lie in the same plane. Loop 1 has radius $\mathbf{1}\mathbf{.}\mathbf{50}\mathbf{}\mathbf{cm}$ and carries $\mathbf{4}\mathbf{.}\mathbf{00}\mathbf{}\mathbf{mA}$. Loop 2 has radius $\mathbf{}\mathbf{2}\mathbf{.}\mathbf{50}\mathbf{}\mathbf{cm}$and carries $\mathbf{6}\mathbf{.}\mathbf{00}\mathbf{}\mathbf{mA}$. Loop 2 is to be rotated about a diameter while the net magnetic field $\overrightarrow{\mathbf{B}}$ set up by the two loops at their common center is measured. Through what angle must loop 2 be rotated so that the magnitude of that net field is $\mathbf{100}\mathbf{}\mathbf{nT}$?

Figure 29-49 shows two very long straight wires (in cross section) that each carry a current of$\mathbf{4}\mathbf{.}\mathbf{00}\mathbf{}\mathbf{A}$ directly out of the page. Distance ${\mathbf{d}}_{\mathbf{1}}\mathbf{=}\mathbf{}\mathbf{6}\mathbf{.}\mathbf{00}\mathbf{}\mathbf{m}$ and distance ${\mathbf{d}}_{\mathbf{2}}\mathbf{=}\mathbf{4}\mathbf{.}\mathbf{00}\mathbf{}\mathbf{m}$. What is the magnitude of the net magnetic field at point P, which lies on a perpendicular bisector to the wires?

Two long straight wires are parallel and $\mathbf{8}\mathbf{.}\mathbf{0}\mathbf{}\mathbf{\text{cm}}$ apart .They are to carry equal currents such that the magnetic field at a point halfway between them has magnitude $\mathbf{}\mathbf{300}\mathbf{}\mathbf{\text{μT}}$. (a) Should the currents be in the same or opposite directions? (b) How much current is needed?

Figure 29-79 shows a closed loop with current $\mathit{i}\mathbf{}\mathbf{=}\mathbf{}\mathbf{2}\mathbf{}\mathbf{A}$. The loop consists of a half-circle of radius $\mathbf{4}\mathbf{}\mathbf{\text{m}}$, two quarter-circles each of radius $\mathbf{2}\mathbf{}\mathbf{m}$, and three radial straight wires. What is the magnitude of the net magnetic field at the common center of the circular sections?

In Fig. 29-4, a wire forms a semicircle of radius $\mathit{R}\mathbf{=}\mathbf{9}\mathbf{.}\mathbf{26}\mathbf{}\mathbf{\text{cm}}$ and two (radial) straight segments each of length $\mathit{L}\mathbf{=}\mathbf{13}\mathbf{.}\mathbf{1}\mathbf{\text{cm}}$. The wire carries current $\mathbf{}\mathit{i}\mathbf{=}\mathbf{34}\mathbf{.}\mathbf{8}\mathbf{}\mathbf{\text{mA}}$. What are the(a) magnitude and(b) direction (into or out of the page) of the net magnetic field at the semicircle’s center of curvature C?