A Doubly Charged Ion with Speed 6

Multiple Choice

A doubly charged ion with speed 6.9 × 10⁶ m/s enters a uniform 0.80-T magnetic field,traveling perpendicular to the field.Once in the field,it moves in a circular arc of radius 30 cm.What is the mass of this ion? (e = 1.60 × 10^-19C) .

A) 11 × 10^-27 kg
B) 6.7 × 10^-27 kg
C) 3.3 × 10^-27 kg
D) 8.2 × 10^-27 kg