Doug, It's not even a coincidence. It just happens to be almost equal. The integral of y=8*e^(-x/.125) between 0 and x0 is this mathematical function of x0: -8*0.125*(e^(-x0/0.125)-1) In this case, when x0=1, the integral equals 0.9997, which is just close to 1. If x0=+inf, the integral equals 1. --Cristian -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Doug Brooks Sent: 3-Jun-12 10:45 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Skin Effect question This question relates to skin effect. Consider a current density function with (surface density) Io=8 and skin depth = .125, unity radius. consider the current density function y=8*e^(-x/.125) integrate the area under this function between 0=<x=<1. The answer is .9997 (according to the tool I am using!) Consider the rectangle formed by the points 0,0, 0,8, .125,8, .125,0 (Note that x=.125 [i.e. at the skin depth] is where the exponent of e in the current density function is -1.) the area under this rectangle is 1.0 (same as the area under the current density function.) Here is my question. Is this a fortunate coincidence or can this identity be proven mathematically? Doug has a new e-mail address dbrooks7@xxxxxxxxxxxxxxx check out the free resources at http://www.ultracad.com ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu