Both Fields at Once?!
For MRI safety, engineers consider the effects of both magnetic and electric fields!Copyright 2004 Microsoft Corporation, One Microsoft Way, Redmond, WA 98052-6399 USA. All rights reserved.
Pertinent to their ongoing investigation of MRI machines, students learn the consequences of a charge being subject to electric and magnetic fields at the same time. The lesson covers the Hall effect, velocity selector and the charge to mass ratio. Through several example problems, students calculate the Hall voltage, which is dependent upon plate width, drift velocity and magnetic field strength. Then they calculate the velocity selector, represented by the ratio of the magnitude of the fields, assuming the strength of each field is known. Students perform a series of calculations to arrive at the charge to mass ratio, and finally, a homework problem set, serving as an evaluation of student progress.
Engineers must understand the combined effects of electric and magnetic fields in order to design safe MRI machines and recognize safety issues. They also apply their understanding of the properties of electric and magnetic fields in applications such as the mass spectrometer. In the provided homework problem set, students use the velocity selector, charge to mass ratio, and the Hall effect to answer questions relevant to the combined effects of electric and magnetic fields.
After this lesson, students should be able to:
- Describe the Hall effect.
- Calculate a Hall voltage.
- Use the charge to mass ratio.