As shown in Fig. 13.1, a beam of particles of charge q enters a region where an electric field is uniform and directed downwards. Its value is 80 kV/m. Perpendicular to E and directed into the page is a magnetic field B = 0.4 T. (i) If the speed of the particles is properly chosen, the particles will not be deflected by these crossed electric and magnetic fields. What speed is selected in this case? (ii) If the electric field is cut off and the same magnetic field is maintained, the charged particles move in the magnetic field in a circular path of radius 1.14 cm. Determine the ratio of the electric charge to the mass of the particles.
Solution:
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