Force of 7 N acts on an object. The displacement is, say 8 m, in
the direction of the force
(Fig. 11.3). Let us take it that the
force acts on the object through
the displacement. What is the
work done in this case?

The earth's magnetic field, with a magnetic dipole moment of 8.0×1022am2, is generated by currents within the molten iron of the earth's outer core. suppose we model the core current as a 3000-km-diameter current loop made from a 1000-km-diameter “wire.” the loop diameter is measured from the centers of this very fat wire.to decide whether this is a large or a small current density, compare it to the current density of a 7.0 a current in a 2.0-mm-diameter wire.