25-14. After passing through velocity selector; stream of ions moving at velocity V enters uniform magnetic field B and is swept into a circular arc of radius r. Derive an equation for the mass of each ion. (6) Calculate the mass of the ion if its charge is 1.6 x 10-"9C, its speed in the field is 2.05 x 10' m/s, the radius of its path is 0.308 m, and the magnetic field strength is 1.36 T. (c) Calculate the mass of the ion in atomic mass units (amu), given that there are 6.02 X 1026 amu in kg: Can you guess what element this ion belongs to?