A uniform magnetic field is parallel to and in the direction of the positive z axis. For an electron to enter this field and not be deflected by the field, the electron must be traveling in which direction?
A) any direction as long as it is in the xy plane.
B) any direction as long as it is in the xz plane.
C) along the positive x axis.
D) along the positive y axis.
E) along the positive z axis.

Question

A uniform magnetic field is parallel to and in the direction of the positive z axis. For an electron to enter this field and not be deflected by the field, the electron must be traveling in which direction?
A) any direction as long as it is in the xy plane. 
B) any direction as long as it is in the xz plane. 
C) along the positive x axis. 
D) along the positive y axis. 
E) along the positive z axis.

Quizplus · Accepted Answer

Since the magnetic field is parallel to the positive z-axis, the only way for an electron to not be deflected by the field is if it is also traveling parallel to the z-axis. So, the electron must be traveling along the positive z-axis (choice E).

A Uniform Magnetic Field Is Parallel to and in the Direction