試題詳解

18. The mass spectrometer. In 1910, W. Aston proposed and constructed an experiment measuring the mass of a charged particle. The key elements of a mass spectrometer are shown in Figure 4. A collimated beam enters the velocity selector. Upon emerging from slit C, these particles of velocity u now enter a region with only a magnetic induction B₀perpendicular to the plane of the diagram. These particles experiencing the Lorentz force traverse a semicircular path (with radius R) until they strike a screen. Find the resulting radius R . 
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