Charging by Induction

Charging by induction is to charge an object without touching the object with any other charged object. This is related to polarization, which is the process of separating opposite charges inside an object.

  

One of the ways to try charging by induction is to use two metal spheres in an experiment. The metal spheres are held up by insulated stands, so charges cannot move between the ground and the spheres. The spheres and the stands are put side by side, so electrons can move freely between the metal spheres. When a negatively charged balloon is placed near the two negatively charged spheres, the negative charges will start to move in the spheres, because similar charges repel. The electrons start to freely move around the surface of the conductor, and the charges move from one sphere to the other. This is an example of polarization. The polarization leaves the metal spheres neutral, but the electrons moving from the spheres separates the positive sphere and the negative sphere.

The induction experiment can also be used with soda cans and styrofoam cups. The cans are taped on the cups, and are placed side by side. A negatively charged balloon is brought near one of the cans. The negative charge near the can repels the electrons to the other can, once the cans are separated, the cans are charged.