AP physics 2 essentials

[dndfuf98]

On question 7.33, there isn't sufficient explanation for the answer. Could you elaborate on that please? I'm not sure what is causing the needle to point toward the top. By the way, does toward the top mean out of the page or just top?

[FizziksGuy]

This is a right hand rule question.  You'll have to think in three dimensions.  As current flows through the wire to the right, a magnetic field is created which travels around the wire.  Above the wire (in the air above the book if you're looking at it on paper), the direction of this field is toward the bottom of the page.  Below the wire (down into the book if you're looking at it on paper), the direction is toward the top of the page.  This relates back to the section on Fields due to Current-Carrying Wires on pages 173-174.