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## Homework Statement

An electron enters a uniform magnetic field B = 0.246 T with its velocity vector making an angle of θ = 49.7 ° with respect to the B vector. Determine the radius r and the pitch p (distance between loops) of the electron's helical path assuming its speed is 3.0 x 106 m/s.

HELP: In considering the circular part of the motion, you can ignore the component of the velocity vector vx along the direction of the magnetic field. (If you like, think of the electron's trajectory as seen by an observer moving along the B direction with speed vx. For that observer, the electron is moving in a circular orbit, rather than a helix.)

HELP: Figure out how long the electron takes to complete one loop of its orbit. How far along the B direction does the electron drift during this time?

## Homework Equations

r=mv/qB

I'm not sure of any others.

## The Attempt at a Solution

I'm still at the finding r stage. So as per the "help" I used said equation, and got 6.943x10

^{-5}as the answer. However, it's not correct. I'm not quite sure what I'm doing wrong.