An electron travels with speed 6.0 106m/s between the two parallel charged plates shown in the figure. the plates are separated by 1.0 cm and are charged by a200 v battery. what magnetic field strength will allow the electron to pass between the plates without being deflected?

3.3 mT

Explanation:

First of all, we need to find the strength of the electric field between the two parallel plates.

We have:

(potential difference between the two plates)

(distance between the plates)

So, the electric field is given by

Now we want the electron to pass between the plates without being deflected; this means that the electric force and the magnetic force on the electron must be equal:

where

q is the electron charge

E is the electric field strength

v is the electron's speed

B is the magnetic field strength

In this case, we know the speed of the electron: , so we can solve the formula to find B, the magnetic field strength: