New podcast plus two digital videos

The Uvision visual podcast site has a new podcast about batteries and currents, based on two conceptual questions from chapter 21.

Also, I have got the links re-established for two digital videos on static electric field behaviors.

1. Static cling shows the electric field, even field lines, for a toy balloon. This to the concept of induced attraction and field lines in chapter 20.
2. Electromagnetic interaction is a digital video of the polarization demonstration shown in Fig. 20-5.