an ideal transmission line has an ideal unit step voltage so

an ideal transmission line has an ideal unit step voltage source connected at its sending node and a resistive load connected at its receiving node.Calculate the relationship between the load impedance and characteristic impedance to produce a transient voltage at the receiving node 1.75 times larger than the voltage applied at the sending node

Solution

In a power system network the characteristics impedance is given by the ratio of square root of series impedance of transmission line(Z) to the shunt admittance of transmission line(Y).   

  Characteristics impedance = sq rt(Z/Y).

Z=R+jX
Y=G+jB

The characteristics impedance is calculated for the transmission line with losses.

  The term Surge impedance is reserved for the special case of loss less line.
  
  For the loss less line the resistance(R) and conductance(G) are zero.

   Now the characteristics impedance of the transmission line is reduced to pure resistance in terms of dimensions.

   Surge impedance = sq rt(L/C)

surge means load impedance