Answer to Question #303017 in Electricity and Magnetism for mika

Question

A proton is moving in the positive x-direction as shown in Figure 2 with a speed of 1.25 × 106 m s −1 . Then, the proton enters the region between the two plates. The potential difference between the plates is 200 V. The electric potential of the upper plate is higher than the electric potential of the lower plate. The separation distance between the plates is 35.0 mm. Determine the direction and the magnitude of the magnetic field that is required between the plates for the proton to continue traveling in a straight line in the positive x-direction.

Answer 1

$v=\sqrt{\frac{2eU}m},$

$B=\frac{mg}{ev}=6.2~mT.$