Unlike other kinds of liquids, volatile liquids
a. evaporate rapidly at a relatively low temperature.
b. ignite readily at a relatively low temperature.
c. flow rapidly at a relatively low temperature.
d. freeze readily at a relatively high temperature.

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.