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23. In a mass spectrometer chlorine ions of mass 35u and charge +5eare emitted f

ID: 1743398 • Letter: 2

Question

23. In a mass spectrometer chlorine ions of mass 35u and charge +5eare emitted from a
source and accelerated through a potential difference of 250 kV.They then enter a
region with a magnetic field that is perpendicular to theiroriginal direction of motion.
The chlorine ions exit the spectrometer after being bent along apath with radius of
curvature 3.5 m. What is the speed of the chlorine ions as theyenter the magnetic field
region?
(u = 1.66 × 10^–27 kg, e = 1.6 × 10^–19C)
A) 2.6 × 10^6 m/s
B) 1.9 × 10^6 m/s
C) 1.2 × 10^6 m/s
D) 1.5 × 10^7 m/s
E) None of the above

Explanation / Answer

V q = energy gained from potential difference V 1/2 m v2 = V q v2 = 2 V q / m = 2 * 2.5 * 10E5 * 5 *1.6* 10E-19 / (35 * 1.67 * 10E-27 ) v2 = 5 * 8 * 1.6 * 10E-14 / (35 * 1.67 * 10E-27 )= 10.9 * 10E12 v = 3.3 * 10E6    none of the above