Trying to understand transmission lines?

Ok so you do want a simple coax cable example?

Yes, current is the movement of charge. For a transmission line, the charge never gets very far, ie one wavelength, before it stops and flows backwards, but the wave continues down the wire. If the end is open, the wave is reflected is phase, ie a positive reflection, and the sum of the two waves in either direction creates a standing wave.

https://en.wikipedia.org/wiki/Standing_wave

http://www.physicsclassroom.com/class/waves/Lesson...

https://www.youtube.com/watch?v=-gr7KmTOrx0

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https://en.wikipedia.org/wiki/Time-domain_reflecto...

I explained the same thing to a co-worker using a tennis ball and rain gutter as an example. So when I asked what happens when the ball reaches the end of the trough, she said "the ball goes down the hole".

The simplest explanation is to compare waves travelling along a canal (parallel-wall container).

The open circuit in a transmission line is like a wall; the wave hits it and bounces back.

It's an oscillation effect producing a standing wave, in either case; current/flow alternates in direction with each half cycle of the oscillation.

Current is flow in either case; voltage is equivalent to pressure (height) of water.

https://www.youtube.com/watch?v=NpEevfOU4Z8

current flows in transmission line in incident wave that travels forward and reflective wave that travels back, the current travels in the speed of light.

since there are two parallel conductors and a wires twisted together act like coils, transmission lines have their own built in capacitors, inductance, that causes current to act weird and travel back to the wire.

An unbalanced RF transmission line looks electrically like a string of inductors and capacitors. The equivalent values of those L's and C's are such that when the transmission line is loaded with a resistor equal to the lines characteristic impedance, then the input of the line will look resistive. When the line is terminated in something other that the lines characteristic impedance, then the L's and C's have reactance that cause the input of the line to look reactive. The line can look capacitive or inductive depending on the length of the line and the applied frequency. An open line can look like a short at the input end if the line length is an odd multiple of 1/4 wavelength. An open line will look open if the line length is an even multiple of 1/4 wavelength.

An open coaxial cable causes a severe mismatch between the impedance of the coax and the impedance of the open circuit. This causes all of the power to be reflected back toward it's source. This condition will set up standing waves along the length of the coax resulting in periodic locations where current is max and Voltage is minimum and other locations where Voltage is max and current is minimum. The net coaxial current from source to opening is zero Amps.

Note: The above may or may not be completely valid.

You mean RF transmission coaxial cables.

RF is a wholly different kettle of fish. I cannot offhand think of any RF circuit that can continue functioning if open circuit, but perhaps an "open circuit" such as a capacitor can allow RF to pass.

Additionally, it is possible to short circuit RF and NOT interfere with RF current passage. That's a neat trick often used at RF. Placing a short of certain dimensions across an RF cable can allow the desired frequency to ignore the short, but can short another RF signal of a different frequency present on the cable to ground.

As the short is a short at DC, it can also be placed in a transmission path to allow such as EMPs from thunderstorms or electricity generated by friction on an antenna, to flow safely to ground without reaching delicate electronics.

NO CURRENT IS FLOWING IN OPEN CIRCUIT !!!