Final answer:
Current is produced in Faraday's apparatus through electromagnetic induction. The changing magnetic field created in the top coil induces an emf and generates a current in the bottom coil.
Step-by-step explanation:
In Faraday's apparatus, a current is produced through the process of electromagnetic induction. When the switch is closed, a magnetic field is created in the top coil. This changing magnetic field induces an electromotive force (emf) in the bottom coil, generating a current. When the switch is opened and closed, the galvanometer registers currents in opposite directions. It is the change in the magnetic field produced by the top coil that creates the current in the bottom coil.