1. The problem statement, all variables and given/known data An electron travelling North with a speed of 8.9x10^6 m/s enters a magnetic field of strength 0.069 T pointing East. In what plane (upward and North-South, upward and East-West, or horizontal) does the electron's orbit lie? 2. Relevant equations 3. The attempt at a solution Since it's an electron, I would normally use the left hand rule to determine the direction of the force acting on the electron which would be upwards. I just don't understand my options. Since it's already travelling along the North-South, would the magnetic force cause the electron to orbit vertically along the North-South since the force is always centripetal? That's what I would guess, but I'm not very confident with that answer.