This is a good introduction to transmission lines:

Transmission Lines, Reflections, and Termination

Refer to this Wikipedia page for the Reflection coefficient

Note: The larger the difference between the load impedance and the transmission line impedance the larger the reflection. When the load impedance is less than the line impedance the reflection is negative (i.e. 180 degree phase shift). When the load impedance is greater than line impedance the reflection is positive.

The two extremes are a short circuit where the reflection coefficient is -1 (no voltage at the shorted end of the cable) and an open circuit (twice the voltage at the open end of a cable).

You can think of voltage at any point on the line as the superposition of the reflected wave (propagating to the left) and the original wave (propagating to the right).

Each transmission line, microstrip, stripline, and coax cable will have a unique propagation velocity depending on it's characteristic impedance, Zo = SQRT(L/C). You can calculate the propagation delay for different length coax cables.

INTRODUCTION TO TRANSMISSION LINES (more detail than you want)