Electron Through a Magnetic Field

[Jimbo57]

Homework Statement

An electron traveling 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?

Homework Equations

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 traveling 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.

 

[gneill]

Your analysis looks okay. As you say, the Lorentz force on the electron will (initially) point vertically upwards. Since centripetal force points towards the center of the orbit, the center lies in a vertical plane containing (or at least parallel to) the N/S axis.

 

[Jimbo57]

Thank you for confirming gneill!