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A mass spectrometer is a device that allows taking measurements of charged particles? masses. Mass spectrometers are used to separate isotopes, i.e. the nuclei with the same charges but different masses (for example, U235 and U238.)
The basis of a mass spectrometer is a chamber with high vacuum. À uniform magnetic field permeates the chamber in the region that lies between the two poles of an electromagnet. Charged particles move into the chamber after passing through the velocity selector. The charges travel through the chamber across the plane that is perpendicular to the magnetic field while a magnetic force acts upon them. The trajectories of these particles are circles of radius
R = mv/qB,
where m and q are the mass and the charge of a particle, v is its velocity, and B is the magnetic field. Having measured the radius of the trajectory with given v and B, one can also find the ratio q/m. When dealing with isotopes (q1 = q2) , mass spectrometer can be used to separate particles with different masses.

Choose two isotopes of any chemical element, and alternate the magnitudes of speed and the magnetic field force. Observe the variance in the radii of these isotope?s circular trajectories.
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