Question

An electron, free to move when placed in an electric field, moves

A. perpendicular to the field lines
B. unaffected by the field
C. along the field lines, in the field direction
D. along the field lines, opposite the filed

Answer 1

An electron placed in an electric field will move along the field lines in the direction opposite to the field. In a magnetic field, it will spiral along field lines if not moving perpendicular to them.

Step-by-step explanation:

The question pertains to the behavior of an electron in an electric field. When an electron, which is free to move, is placed in an electric field, it will experience a force due to the field. According to Figure 18.26, when an electric field is applied to a conductor, free charges such as electrons move until there is no component of the field parallel to the surface, indicating motion along the field lines. Therefore, an electron will move along the electric field lines in the direction opposite to the field (since electrons are negatively charged and electric fields exert forces from positive to negative).

However, if we're discussing a magnetic field, the situation is different. When not moving perpendicular to magnetic field lines, electrons will spiral along the field lines, as noted in Figure 22.21. The motion of electrons in electric and magnetic fields is determined by the Lorentz force, which states that the electric component will be along the field lines, and the magnetic component will be perpendicular to both the field and the velocity of the electron.