- 14

- 3

- Homework Statement
- The statement is below.

- Homework Equations
- F = qv × B

The text showed if Fnet = 0 (with F from magnetic fields and electric field), then v = E/B . And we can measure m/e (last equation in the image).

My question is, by assuming F = 0, change in y should also be 0 , so the denominator of right side of the m/e equation must be zero. And the equation doesn't hold. Am I wrong?