Hi In Biot Savarts Law we say dH(at a point) is proportional to I*dl*Sin(angle) and inversely proportional to square of the distance from that point to the conductor Then finally we have constant of proportionality k= 1/4*pi , my question is how did they come up with this value for k? Thanks Haritha --------------------------------- Do you Yahoo!? The New Yahoo! Shopping - with improved product search ------------------------------------------------------------------ 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 archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu