[To Parent Directory]10/12/2020 11:40 AM lecture1310/12/2020 11:43 AM lecture_13a_magnetic_force 10/9/2020 12:36 PM lecture_13a_magnetic_force10/12/2020 12:47 PM lecture_13b_motion_in_B_field 10/9/2020 12:37 PM lecture_13b_motion_in_B_field