# An electron moving north encounters a uniform magnetic field if the magnetic field points east what is the direction of the magnetic force on the electron?how can you find the direction of the magnetic force

The magnetic force for an electron in a magnetic field is given by

`F_L= -e(v xx B)`

where x is the vectorial product between `v` and `B` .

Whenever one has a vectorial product resulting vector follows the rule of the right screw: one rotate the first vector (`v` in this case) over the second vector (`B` here) after the direction a right screw follows and obtain the direction of the resultant.

There is also an alternative to this rule, known as rule of right hand: if right hand fingers are in the direction of first vector (`v` ) and thumb in the direction of the second vector (` ` `B` ) the resultant force is entering the hand palm.

Because of the minus sign in front of the vectorial product (coming from the negative charge of the electron) in the case of the electron moving in magnetic field, the direction of magnetic force is reversed.

The figure is below attached.

The magnetic force is perpendicular to the paper, out of the paper.