An electron in a cathode-ray beam passes between 2.5 cm-long parallel-plate electrodes that are 5.0 mm apart. A 2.0 mT, 2.5-cm-wide magnetic field is perpendicular to the electric field between the plates. The electron passes through the electrodes without being deflected if the potential difference between the plates is 600 V.
a. What is the electron’s speed?
b. If the potential difference between the plates is set to zero, what is the electron’s radius of curvature in the magnetic field?