# Direction of force

1. Apr 28, 2004

### UrbanXrisis

B-Field is going into the page. An electron has a velocity to the left. Force is then downwards correct?

2. Apr 28, 2004

### Staff: Mentor

No. The force is given by F = qV x B. Using the right-hand rule, and noting that the electron has a negative charge, I get that the force is up the page.

3. Apr 28, 2004

I forgot which hand is my right one. It's not the left one, right?

4. Apr 28, 2004

### UrbanXrisis

My hands are faced down...B field into the page, means fingers curled, and if the thumb is pointing to the left, the the force is acting down.

5. Apr 28, 2004

### jamesrc

When you cross the velocity vector (pointing to the left) by the magnetic field vector (pointing into the page), your thumb ends up pointing down. But, as DocAl said, because we are looking at an electron, the value of the charge (q) is negative (q = -1.6*10^-19 C). The force is therefore pointing in the negative down direction or, as we say where I'm from, up.