the voltage-drop between the sending-end and receiving-end of any transmission line is based on four parameters: resistance; reactance; conductance; and capacitance.
The first two are called the series-impedance of the line, while the last two yield the lines' shunt-admittance. The formula (before computers) for determining the relationship between the sending and receiving-end voltages is considered rather tedious.
However, it was recognized that the formula could be approximated based on line-length. That is, for short-lines the series-impedance was the dominant feature, while shunt-admittance, principally the capacitive component, was the dominant feature of long lines.
In conclusion, the longer the line, the more dominant the capacitance effect, resulting in receiving-end voltage being higher than sending-end.
Would you like to know what line-length defines the short, medium, and long-line?
