1. An electron is travelling in the +ve x-direction of an inertial frame T. An acceleration is given to the electron in the +ve y-direction with as large as magnitude as possible. How do I specify directions of the electric and magnetic fields that will achieve this? Why are the choice of field directions unique? 2. 3. Surely the elctric field is pointing in the -ve y direction but not sure about the magnetic field. I'm not sure though. Also have no clue why it would be unique!