A lightning bolt may carry a current of 1.00 ✕ 104 A for a short time interval. What is the resulting magnetic field 134 m from the bolt? Assume that the bolt extends far above and below the point of observation.

Answer 1

Isn't this Biot-Savat law?

http://dev.physicslab.org/Document.aspx?doctype=3&filename=Magnetism_BiotSavartLaw.xml