Reagan, PHET) Purpose: Students will use the radioactive decay rate and original-daughter element ratios of Carbon-14 and Uranium-238 to determine the ages of different objects.
A stronger magnetic field deflects more cosmic rays away from the Earth.
Overall, the energy of the Earth's magnetic field has been decreasing, so more C is being produced now than in the past.
Obviously, this works only for things which were once living.
It cannot be used to date volcanic rocks, for example.
The rate of decay of N in 5,730 years (plus or minus 40 years).