An electron moves east in a magnetic field directed north. The magnetic force on the electron points

1. The magnetic force on a charge is F = qv × B. 2. Take east as +x, north as +y, up as +z. Then v × B = x̂ × ŷ = ẑ (upward). 3. For a positive charge, the force would be upward; for the electron (charge -e), the force flips direction. 4. So the magnetic force on the electron points downward. _Source: syllabus Physics Ch 4 "Moving Charges and Magnetism", §4.2.2_