Electrodynamics/Tutorials/4/1/3

Video Intro

Hi, this is Jonathan Gardner.

We're covering [section reference] of Griffiths Introduction to Electrodynamics.

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4.1.3 Polarization(?)

Polar Molecules

Some molecules have a dipole moment already added. Water (H20) has a very strong dipole moment, when no electric field is present.

Torque

What happens when they are placed in an electric field? There is a force one way on the positive, and the other way on the negative. This creates a torque.

If the field is mostly uniform where the molecule is, then there is no net force, so the molecule isn't going to move one way or the other.

Force

In a non-constant electric field, the force on one may be stronger than the other, creating a net force. This could cause the molecule to move one way or the other, depending on its dipole moment.