Capacator with moving dielectric

[davidY]

suppose you had a capacator and a free to move dialetric, which was outside of it, and you attatch a voltage to the capacator. the dialetric will move in. however, does anybody know what force and where the force is that causes the dialetric to move in?

 

[Andrew Mason]

suppose you had a capacator and a free to move dialetric, which was outside of it, and you attatch a voltage to the capacator. the dialetric will move in. however, does anybody know what force and where the force is that causes the dialetric to move in?

The dielectric contains polar molecules, that is molecules which have a + and a - side. So they align with the electric field (e.g. + side of molecule toward - plate). This means the dielectric experiences a force toward the plates. The force depends on the number and degree of polarity of the molecules in the dielectric, which determines the k of the permitivity.

AM

 

[davidY]

thanks. by the way, would it be the fringing effects of the electric fields that cause the force? (as the non fringing electric field would be pointing in the direction of one plate to another)

 

[Andrew Mason]

thanks. by the way, would it be the fringing effects of the electric fields that cause the fnorce? (as the non fringing electric field would be pointing in the direction of one plate to another)

No. The molecules in the dielectric are affected by the entire field of the plate. Have a look at this, for example:

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

AM