Magnetic and Electric Fields in Nature and Technology . In order for an electron to pass through both the electric and magnetic fields without being deflected, the magnetic force ( ) must be identical in magnitude to the electric force ( 1). Derive an expression for the velocity of the electron when these two forces are equal to one another. ousmom s ations blott s . If the electric field is turned off, what kind of motion will result from the application of only the magnetic field? . If the magnetic force ( ) is an inward force ( ) when acting alone, determine an expression for the charge-to-mass ratio of an electron (q/m) by first equating Fm and Fin. . Why was determining the charge-to-mass ratio of an electron considered important? D 2. Post your responses to the discussion area for your class. Read the responses of at least two other students. Module 4: Lesson 2 AssignmentD 1. Research Thomson's work on the charge-to-mass ratio and answer the following: . If both an electric field and a magnetic field exert a force on a moving electron, could they be arranged in such a manner that each force cancels the other out, allowing the electron to pass through a CRT without being deflected? Sketch the orientation of the electric and magnetic fields to show that an electron travelling west could pass through each field simultaneously without being deflected. Label your diagram. + 2009 Alberta Education