Question

By considering the molecules of an insulator, explain how an insulator can be overall neutral but carry a surface charge when polarized.

a) When polarized, insulator molecules redistribute their charges, creating a surface charge.

b) Insulator molecules lose electrons, creating an overall neutral surface charge.

c) Insulator molecules gain protons, creating an overall neutral surface charge.

d) Insulator molecules become conductive, carrying a surface charge.

Answer 1

When a charged rod is brought near a neutral insulator, polarized molecules create a surface charge based on the attraction of opposite charges.

Step-by-step explanation:

When a charged rod is brought near a neutral insulator, the distribution of charge in the insulator's atoms and molecules is shifted slightly. Opposite charges are attracted to the charged rod, while like charges are repelled. This creates a polarization in the insulator, where the opposite charges are closer to the surface and create a surface charge.

For example, when a positively charged glass rod is brought near a neutral insulator, the positive charges in the insulator's molecules are attracted to the glass rod, creating a negative surface charge on the insulator. Similarly, a negatively charged rod would attract positive charges and create a positive surface charge.

This polarization effect occurs because of the electrostatic force, which decreases with distance. The attraction of opposite charges is stronger than the repulsion of like charges, resulting in a net attraction and the formation of a surface charge on the insulator.