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Mass spectrometer - atoms moving in magnetic field

Imagine that we give N2(+), O2(+) and (NO)+ ions the same velocity of 30.0 km/s and then send them into a mass spectrometer where the magnetic field strength is B=8.5MN/C. How far would the spot on the photographic plate be from the entry point for each ion, assuming that each ion completes one-half of an orbit. The atomic mass of a nitrogren atom is 14.0031 amu and oxygen is 15.9949 amu, where 1 amu = 1.6605 x 10^-27 kg

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mass of O2 ions mo = 2*15.9949 * 1.66 * 10^-27 kg
mass of N2 ions mn = 14.0031 * 1.66 * 10^-27 kg
mass of NO ions M = 29.998 * 1.66 * 10^-27 Kg

The charged particle undergoes circular motion, with,

mv^2 /R = q v B


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