capacitive effect

Why not?

| why capacitive effect s neglected n short transmission line?

why english s not n your native language?

When values are so small as to be insignificant it is comon practice to ignore them.

The capacitance is directly proportional to the area of the cross section. In transmission lines area is the product of thickness of the conductor and the length. As we know the thickness is going to be few centimeters. Hence the capacitance mainly depends on the lenght of the transmission line. Hence only if the length is large the capacitance value will be cosiderable. In short transmission line length is small, hence the capacitance effect is negligible.

While the total capacitance of a transmission line is directly proportional to length, the capacitance per unit length is not directly proportional to the conductor cross-section (In addition, the effects of this capacitance is not directly proportional to length). I suggest that you look up the relationships dealing with capacitance per unit length for a transmission line. Then look up the "telegrapher's equations". Your model has problems.

However, beyond these academic quibbles, I do agree with Tim Perry and you that for a short line, the capacitance is negligable.