2. Putting It Together: The Mass Spectrometer (3 pts) Potassium ions (charge -e, mass m = 39 mp) are accelerated from rest at plate A through a voltage difference of AV = 5 kV to plate B. Some of the ions pass through a small slit in plate B to enter into a region of uniform magnetic field (the shaded region in the diagram). mp is the mass of a proton, 1.67 10-27 kg. a) Which plate is at a higher potential, A or B? Calculate the speed of the K ions when they reach the slit in plate B. 10 cm AV 10 cm C Detector 10 cm b) When the ions enter the region of constant magnetic field, they experience a force that is perpendicular to their velocity. Using Newton's Laws, what must be the magnitude and direction of this force if these ions are to follow a curved path of radius r = 10 cm? c) Find the magnitude and direction of the magnetic field needed for the force you found in part (b).