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Name:_____________________________________________________ Section: A B Quiz 03D: Charged Particles in a Magnetic Field Four different types of charged particles (ions), labeled P, Q, R, S, are mixed together in a particle beam, initially traveling straight upward at the same speed, in the absence of any force, as shown in Figure below. (Neglect gravity!) The particles then enter a non-­‐zero uniform magnetic field, B, pointing out of plane of drawing, and the beam splits apart: each particle type now travels on a different semi-­‐circular trajectory, with P-­‐ and R-­‐particles turning rightward and Q-­‐ and S-­‐particles turning leftward, as shown below. The particles carry charges qP , qQ , qR , qS and masses mP , mQ , mR , mS , for particles of type P, Q, R, S, respectively. Y
Q
S
B (out)
R
P
B=0
__________________________________________________________________________________________ (a) Find the direction of a Q-­‐particle’s velocity vector, v, as it passes through the point marked “Y” on its semicircular trajectory. State your answer as one of these six: (A) leftward (B) rightward (C) upward (D) downward (E) out of plane of drawing (F) into plane of drawing __________________________________________________________________________________________ (b) Find the direction of the magnetic force F acting on a Q-­‐particle, as it passes through “Y”. State your answer for the direction as in part (a), using: (A) (B) (C) (D) (E) (F) __________________________________________________________________________________________ (c) Find the signs of the charges, qP , qQ , qR , qS , carried by type P, Q, R and S particles, respectively: qP : + or − ? qQ : + or − ? qR : + or − ? qS : + or − ? __________________________________________________________________________________________ (d) Assume the magnitudes of all 4 particle charges are the same: |qP| = |qQ| =| qR|=|qS| . Rank order their masses, mP , mQ , mR , mS , from highest to lowest. Write, e.g.: mS > mR > mQ > mP if S is heaviest, R is 2nd heaviest, Q is 3rd heaviest, P is 4th heaviest. Hint: Compare their semi-­‐circles! __________________________________________________________________________________________ (e) Assume all 4 particle masses are the same: mP = mQ = mR = mS . Rank order the magnitudes of their charges, |qP|, |qQ|, |qQ|, |qS|, from lowest to highest. Write, e.g.: |qP| < |qQ| < |qR| < |qS|, if P has the lowest, Q the 2nd lowest, R the 3rd lowest, S the 4th lowest magnitude of charge. Hint: Compare their semi-­‐circles! __________________________________________________________________________________________