In what way do you not get the right answer ? The field should be very very small. Especially when compared to the earth's field and any other equipment near it. Also beware of CGS units. Many constants are given in CGS you need to convert to MKS to use them. Peter -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics