A beam of protons traveling at $1.20 \mathrm{~km} / \mathrm{s}$ enters a uniform magnetic field, traveling perpendicular to the field. The beam exits the magnetic field, leaving the field in a direction perpendicular to its original direction (Fig. E27.22). The beam travels a distance of $1.18 \mathrm{~cm}$ while in the field. What is the magnitude of the magnetic field?