In: Physics
Describe the physics and draw an illustration of charge polarization.
To illustrate this induced movement of electrons, we will consider an aluminum pop can that is taped to a Styrofoam cup. The Styrofoam cup serves as both an insulating stand and a handle. A rubber balloon is charged negatively, perhaps by rubbing it against animal fur. If the negatively charged balloon is brought near the aluminum pop can, the electrons within the pop can will experience a repulsive force. The repulsion will be greatest for those electrons that are nearest the negatively charged balloon. Many of these electrons will be induced into moving away from the repulsive balloon. Being present within a conducting material, the electrons are free to move from atom to atom. As such, there is a mass migration of electrons from the balloon's side of the aluminum can towards the opposite side of the can. This electron movement leaves atoms on the balloon's side of the can with a shortage of electrons; they become positively charged. And the atoms on the side opposite of the can have an excess of electrons; they become negatively charged. The two sides of the aluminum pop can have opposite charges. Overall the can is electrically
neutral; it's just that the positive and negative charge has been separated from each other. We say that the charge in the can has been polarized.
