Why does carbon dating not work for materials older than about 50,000 years?

Holes drilled several kilometers into earth’s crust provide direct evidence about earth’s interior in the form of

A1.5m wire carries a 2 a current when a potential difference of 52 v is applied. what is the resistance of the wire?

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.