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1. Fig 1 shows a mass spectrometer not unlike the one on display on the second f

ID: 1311009 • Letter: 1

Question

1. Fig 1 shows a mass spectrometer not unlike the one on display on the second floor of the science building. It is used to measure the charge to mass ratios of different ions. The sample is ionized and then accelerated through a potential difference ?V and then they enter a region of uniform magnetic field. The field bends the ions into circular trajectories. After traveling a half circle they strike the wall or a small opening into the detector. As the potential difference changes, different ions make it into the detector.       Typical values are B = 0.20 T, and the distance between entrance and exit holes d = 8.00 cm. What potential difference ?V is needed to detect a) N2+

Given significant figures you can find and were given, what is the size of the hole of the detector you'd make?

Figure 1

Explanation / Answer

Assuming mass of N2+ ion to be m,
m = (14.0031 * 1.6604 x 10-27 kg) = 2.325 x 10-26 kg
q = 2e = 3.20 x 10-19 C

The electric potential energy, PE (qV) is transferred to kinetic energy, KE (