The diagram below shows the position of a long straight wire perpendicular to the page and a set of directions labeled A through H.When the current in the wire is directed up out of the page,the direction of the magnetic field at point P is
A)E.
B)F.
C)G.
D)H.
E)A.

Question

The diagram below shows the position of a long straight wire perpendicular to the page and a set of directions labeled A through H.When the current in the wire is directed up out of the page,the direction of the magnetic field at point P is 
A)E. 
B)F. 
C)G. 
D)H. 
E)A.

Quizplus · Accepted Answer

According to the right-hand rule, if the current is directed up out of the page, then the magnetic field lines will wrap around the wire in a counterclockwise direction when viewed from above. At point P, the magnetic field lines are going into the page. To determine the direction of the magnetic field, we need to use the right-hand rule again. If we curl our right-hand fingers along the direction of the magnetic field lines (into the page), then our thumb will point in the direction of the magnetic field. Using this rule, we can see that the magnetic field at point P is in the direction of option C) G.

The Diagram Below Shows the Position of a Long Straight