How to tell that the magnetic field is going into the page

[Perseverence]

I attached the image of the problem . I'm sorry if it is unreadable. It essentially says that there is a parallel plate capacitor with a uniform electric charge in the space between the plates. And a uniform magnetic charge is in the space between the plates which is produced by another device. The velocity of a charge moves towards the right of the page. the given information in the attached problem, it's clear that the left hand rule is used with the thumb pointing to the right. But I don't see any information that would indicate why the magnetic field will be going into the page. It seems that the magnetic fields could be just as usually be going down the page or up the page.

 

[mfb]

"x" denotes a field going into the paper, a circle with a dot in the center denotes a field coming out of the plane. You can imagine them as seeing the tail and head of an arrow, respectively. This is purely a convention.

 

[Perseverence]

"x" denotes a field going into the paper, a circle with a dot in the center denotes a field coming out of the plane. You can imagine them as seeing the tail and head of an arrow, respectively. This is purely a convention.

I understand that those are the symbols for showing the direction of the field. But I'm trying to figure out how they derived that direction in the first place from the given information.

 

[Perseverence]

I understand that those are the symbols for showing the direction of the field. But I'm trying to figure out how they derived that direction in the first place from the given information.

I understand the left and right-hand rules, but from the given problem there doesn't seem to be enough information to know which direction the magnetic field would be going. Somehow they infer that it is going into the page

 

[Perseverence]

"x" denotes a field going into the paper, a circle with a dot in the center denotes a field coming out of the plane. You can imagine them as seeing the tail and head of an arrow, respectively. This is purely a convention.

Ohhhh duh! I understand what you were saying now! Goodness gracious! Those x''s are not arbitrary symbols on this problem. You are a lifesaver. I know it seemed really obvious to you and now it seems really obvious to me.

Thank you thank you thank you thank you thank you! Physics Forum rules!