# speed of propagation

#### darsie

Joined Feb 19, 2010
15

"With electricity, the overall effect from one end of a conductor to the other happens at the speed of light: a swift 186,000 miles per second!!!"

While it does happen at the speed of light, IMHO, it is the speed of light in the conductor, IMHO, which is (considerably) less than the speed of light in vacuum, 186,000 miles per second.

#### JoeJester

Joined Apr 26, 2005
4,074
Actually that approximate figure is for the vacuum of space. In the atmosphere it's affected by the index of refraction, and slowed further by the propagation path ... whether in the air or in a conductor. But, that's only if you wanted to get specific.

#### Wendy

Joined Mar 24, 2008
21,840
There are quite a few areas where we will not be getting specific. The book is a general reference. For example, Antenna theory covers what you are talking about in depth.

#### JoeJester

Joined Apr 26, 2005
4,074
At least the ebook should state it's "approximately"

#### studiot

Joined Nov 9, 2007
5,003
While it does happen at the speed of light, IMHO, it is the speed of light in the conductor, IMHO, which is (considerably) less than the speed of light in vacuum, 186,000 miles per second.
Why should it be the speed of light in the conductior?

The signal travels along the conductor surface (are you familiar the skin effect?).

So joejester is right in saying the speed is approximately that of light in vacuuo.

#### BillB3857

Joined Feb 28, 2009
2,493
Haven't any of you ever seen a coiled section of coax used as a delay line?