Which statement best describes the behavior of charge during polarization of an insulator?

Which statement best describes the behavior of charge during polarization of an insulator?

• A. The material gains a net charge.
• B. The surface molecules shift electrons creating a temporary polarization that vanishes when the external charge is removed.
• C. The insulator conducts electricity freely.
• D. The object becomes permanently charged after the external charge is removed.

Answer: (B)

Polarization occurs when an external electric field causes bound charges inside an insulator to shift slightly, forming tiny dipoles. Since insulators don’t have free charges that can move through the material, there is no net transfer of charge into or out of the object. The induced dipoles depend on the external field and disappear once the field is removed, so the material returns to its unpolarized state. The statement that best describes this is that surface electrons shift to create a temporary polarization that vanishes when the external charge is removed. The other possibilities imply gaining net charge, free conduction, or permanent charging, which polarization does not entail.

Polarization occurs when an external electric field causes bound charges inside an insulator to shift slightly, forming tiny dipoles. Since insulators don’t have free charges that can move through the material, there is no net transfer of charge into or out of the object. The induced dipoles depend on the external field and disappear once the field is removed, so the material returns to its unpolarized state. The statement that best describes this is that surface electrons shift to create a temporary polarization that vanishes when the external charge is removed. The other possibilities imply gaining net charge, free conduction, or permanent charging, which polarization does not entail.