A coil lies flat on a tabletop in a region where the magnetic field vector points straight up. The magnetic field vanishes suddenly. When viewed from above, what is the sense of the induced current in this coil as the field fades? a. The induced current flows counter-clockwise.
b. The induced current flows clockwise.
c. There is no induced current in this coil.
d. The current flows clockwise initially, and then it flows counter-clockwise before stopping.

Option B - The induced current flows counter-clockwise.

Explanation:

Faraday's law of electromagnetic induction states that whenever a conductor is placed in a changing magnetic field, an electromotive force is induced and that if the conductor circuit is closed, a current is induced which is the induced current. The magnitude of the EMF induced in the coil is therefore proportional to the rate of change of magnetic flux throughout the coil.

Meanwhile, the direction of the induced current is given by Lenz's law which states that the direction of the induced current will oppose the change in electromagnetic force that produced that current.

Since the magnetic field points upwards, the induced current will move in a direction to the left which is counterclockwise

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia