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Magnetism and Centripetal force question 
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#1
Jun1207, 11:04 PM

P: 1

1. The problem statement, all variables and given/known data
One method for determing masses of heavy ions involves timing their orbital period in a known magnetic field. What is the mass of a singly charged ion that makes 7.0 revolutions in 1.3 x 10^3 seconds in a 4.5 x 10^2 T field. a) 2.1x10^25 kg b) 1.3x10^24 kg c) 6.5x10^23 kg a) 5.0x10^20 kg 2. Relevant equations I'm not sure of which equation to use. Maybe.... Fc = Fb m4(pi^2)r/T^2 = QvB 3. The attempt at a solution m4(pi^2)r/(1.3x10^3s/7)^2 = Qv(4.5x10^2) This might be the wrong formula. 


#2
Jun1207, 11:43 PM

Sci Advisor
HW Helper
P: 6,653

If [itex]mv^2/r = qvB[/itex] where [itex]v = 2\pi r/T[/itex] then: [tex]qB = m2\pi/T[/tex] [tex]m = qBT/2\pi[/tex] Just plug in the numbers. AM 


#3
Jun1307, 06:09 AM

P: 137

One caution:
In the previously cited equation [tex]m = qBT/2\pi[/tex], T is the orbital period = (1.3 x 10^3)/7 sec 


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