Before entering a mass spectrometer, ions pass through a velocity selector consi

Question

Before entering a mass spectrometer, ions pass through a velocity selector consisting of parallel plates separated by 1.5 mm and having a potential difference of 131 V. The magnetic field between the plates is 0.42 T. The magnetic field in the mass spectrometer is 1.2 T. (a) Find the speed of the ions entering the mass spectrometer. m/s You currently have 0 submissions for this question. Only 10 submission are allowed. You can make 10 more submissions for this question. (b) Find the difference in the diameters of the orbits of singly ionized^238 U and^235 U. (The mass of a^235 U on is 3.903 times 10^-25 kg.) mm You currently have 0 submissions for this question. Only 10 submission are allowed. You can make 10 more submissions for this question.

Explanation / Answer

V = 131 V , B1 = 0.42 T, d = 1.5 mm, B2 = 1.2 T

(a) net force along vertical direction is zero

Fe - Fm = 0

qE - qvB = 0

v = E/B

E = V/d

v = V/dB = 131/(0.0015*0.42)

v = 2.08*10^5 m/s

(b)

Dd = d238 - d235

magnetic force = centripetal force

qvB = mv^2/r

r = mv/qB

d = 2mv/qB

Dd = (2v/qB)(m238 - m235)

Dd = (2*2.08*10^5)(238-235)(1.6606*10^-27)/(1.602*10^-19*1.2)

Dd = 10.8 mm

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