- #1
Pushoam
- 962
- 51
Forces on dielectrics
I found difficulty in understanding this topic from Griffith.
Here, while calculating F, in eqn. 4.61 , Griffith doesn't bother about energy stored in fringing field.
So, even if I assume that there is no fringing field, then following the above procedure, I can say that there is an attractive force acting on the dielectric and this force must be due to something other than fringing field.
Are the following conclusions correct?
1) The force due to fringing field pulls the dielectric as the force due to the uniform field is perpendicular to the dielectric surface.
2) The energy stored in the uniform field gets changed in this process. The energy stored in fringing field remains constant. This means that work is being done by the force due to uniform field. But the first conclusion says that the force due to uniform field doesn't work on the dielectric.
I need help here in understanding this point.
In eq. 4.7, force due to battery is constant (as both V and ## \frac { dC } { dx} ## are constant ) . So, the surface charge density changes. Right?
I found difficulty in understanding this topic from Griffith.
Here, while calculating F, in eqn. 4.61 , Griffith doesn't bother about energy stored in fringing field.
So, even if I assume that there is no fringing field, then following the above procedure, I can say that there is an attractive force acting on the dielectric and this force must be due to something other than fringing field.
Are the following conclusions correct?
1) The force due to fringing field pulls the dielectric as the force due to the uniform field is perpendicular to the dielectric surface.
2) The energy stored in the uniform field gets changed in this process. The energy stored in fringing field remains constant. This means that work is being done by the force due to uniform field. But the first conclusion says that the force due to uniform field doesn't work on the dielectric.
I need help here in understanding this point.
In eq. 4.7, force due to battery is constant (as both V and ## \frac { dC } { dx} ## are constant ) . So, the surface charge density changes. Right?