Electric field in coaxial cable

[oocelik]

Every physics books show that wave prograpation in coxial cable is TEM wave, like in the picture. But we know that J=σ E from ohms law, which says current in same direction with E field, which is not the case here. What do you think the reason is ?

 

[Dale]

Hi oocelik, welcome to PF!

The E field is along the axis of the cable inside the conductors. It has a perpendicular component between the conductors. The change in direction is caused by surface charges.

Here is a detailed calculation: http://depa.fquim.unam.mx/amyd/arch...ia_a_otros_elementos_de_un_circuito_20867.pdf

 

[oocelik]

Hello Dale,

Thank you for the reply. But I am talking about the ideal case where the cable has infinite conductivity and progpagation is pure TEM wave, which makes it sure that there is no "longitudinal" (i.e Ez=0) along the cable by definition. In this case, what force acts on the charges to flow down the cable ?