Answer / iamdon

Characteristic impedence of overhead line=400 ohm
Characteristic impedence of underground cable=40 ohm

Characteristic impedence= Square root of (L/C).

In case of overhead lines L dominates so higher
Characteristic impedence.
In case of underground cables C dominates(conductors are
very close to each other) so lower Characteristic impedence.

Author:arbelectbit@yahoo.com

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