Electric Pressure on a Charged Surface due to External EF

[gracy]

Why he did not consider parallel force?Will parallel component of electric field not produce electric pressure on the surface?

 

[Bystander]

The parallel component can only produce/result in a shearing force ; zero net pressure. Or put another way, it is orthogonal to the direction necessary to produce movement.

 

[gracy]

You mean shear force does not exert pressure?

 

[cnh1995]

You mean shear force does not exert pressure?

Shear force will be responsible for surface tension, as he said in the video. Pressure will be due to the force normal to the area.