Final answer:
An oscillating magnetic field induces eddy currents in a conducting sheet of low resistivity, creating a shielding effect above the sheet that prevents the field from affecting a conductive loop placed there.
Step-by-step explanation:
When an oscillating magnetic field interacts with a conducting sheet of low resistivity, it induces an electromotive force (emf) within the conductor. According to Faraday's Law of Electromagnetic Induction, a changing magnetic field will induce circulating currents called eddy currents in the conductor. These eddy currents, in turn, produce their own magnetic field that opposes the original changing magnetic field, which is Lenz's Law.
As a result, the region above the conductor is shielded from the changing magnetic field, noting that only changing fields induce an emf, and thus static magnetic fields would not be shielded.
Considering a conducting loop above the sheet, the oscillating magnetic field will not be present in the region above the sheet due to this shielding, and thus, no emf would be induced in the loop. If the field were static, however, the static magnetic field would penetrate the region since it doesn't induce currents in the conductor to shield against itself.