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BIO Magnetic fields and MRI. Magnetic resonance imaging (MRI) is a powerful imaging method that, unlike x-ray imaging, can make sharp images of soft tissues without exposing the patient to potentially damaging
Figure 20.76
Problems 86-88.
An important consideration is that the ret magnet field of any nucleus, except for that of hydrogen (which has only a proton), consists of contributions from both protons and neutrons. If a nucleus has an even number of protons and neutrons, they pair in such a way that half of the protons have spins in one orientation and half have spins in the other orientation. Thus the net magnetic moment of the nucleus is zero. Only nuclei with a net magnetic moment are candidates for MRI. Hydrogen is the atom that is most commonly imaged.
86. If a proton is exposed to an external magnetic field of 2 T that has a direction perpendicular to the axis of the proton’s spin, what is the torque on the proton?
- A. 0
- B. 1.4 × 10−26 N · m
- C. 2.8 × 10−26 N · m
- D. 0.7 × 10−26 N · m
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