If an electron in an electron beam experiences a downward force of 2.0x10^-14N while traveling in a magnetic field of 8.3x10^-2T west, what are the direction and the magnitude of the velocity?

north

Explanation:

When a charged particle moves in a magnetic field, the particle experiences a force given by the formula:

where

q is the magnitude of the charge

v is its velocity

B is the magnetic field

is the angle between the directions of v and B

In this problem,

(charge of the electron)

(strength of magnetic field)

(force)

Therefore, the velocity is

The direction of the force is perpendicular to both the direction of the velocity and the magnetic field, and it can be found using the right-hand rule:

. Thumb: direction of the force (downward) --> however the charge is negative, so this direction must be reversed: upward

- Middle finger: direction of the field (west)

- Index finger: direction of velocity --> north

So, the electron is travelling north.