The magnitude of the magnetic field 50 cm from a long, thin, straight wire is 8.0 µT. What is the current through the long wire?
A long, straight, horizontal wire carries a left-to-right current of 20 A. If the wire is placed in a uniform magnetic field of magnitude T that is directed vertically downward, what is the resultant magnitude of the magnetic field 20 cm above the wire?
A typical current in a lightning bolt is A. Estimate the magnetic field 5.0 m from the bolt.