What is the direction of the magnetic field if an electron moving in the positive x direction experiences a magnetic force in the positive z direction

Given :

An electron moving in the positive x direction experiences a magnetic force in the positive z direction.

To Find :

The direction of the magnetic field.

Solution :

We know, force is given by :

Here, q = -e.

Now, for above condition to satisfy :

So,

Therefore, direction of magnetic field is negative y direction.

Hence, this is the required solution.

beta is electron from nucleus

something from nucleus has changed, but charge must be same for cons of charge