Material Detail

Lecture 8: Polarization, Dielectrics, The Van de Graaff, More on Capacitors

Lecture 8: Polarization, Dielectrics, The Van de Graaff, More on Capacitors

This video was recorded at MIT 8.02 Physics II: Electricity and Magnetism - Spring 2002. "Electric fields can induce dipoles in insulators. Electrons and insulators are bound to the atoms and to the molecules, unlike conductors, where they can freely move, and when I apply an external field -- for instance, a field in this direction, then even though the molecules or the atoms may be completely spherical, they will become a little bit elongated in the sense that the electrons will spend a little bit more time there than they used to, and so this part become negatively charged and this part becomes positively charged, and that creates a dipole. I discussed that with you, already, during the first lecture, because there's something quite remarkable about this, that if you have an insulator -- notice the pluses and the minuses indicate neutral atoms -- and if now, I apply an electric field, which comes down from the top, then, you see a slight shift of the electrons, they spend a little bit more time up than down, and what you see now is, you see a layer of negative charge being created at the top, and a layer of positive charge being created at the bottom. That's the result of induction, we call that also, sometimes, polarization. You are polarizing, in a way, the electric charge..."

Quality

  • User Rating
  • Comments
  • Learning Exercises
  • Bookmark Collections
  • Course ePortfolios
  • Accessibility Info

More about this material

Comments

Log in to participate in the discussions or sign up if you are not already a MERLOT member.