• A wire pointing north-south is dropped freely towards earth. Will any potential difference be induced across its ends?
• If the wire kept in the east-west direction be dropped freely, then?

The magnitude of induced emf in a circuit is equal to the rate of change of magnetic flux linked with it.
 $E=\left|\frac{d\varphi }{dt}\right|$

Condition for maximum flux linked to the surface: Plane of the surface is perpendicular to the magnetic field

Condition for minimum flux linked to the surface: Plane of the surface is parallel to the magnetic field

Case I:(wire pointing north-south)

Here, the the ends of the wire are pointed towards the magnetic field of Earth, which is in north-south direction.
Hence, minimum flux is linked to the surface and no emf is induced in the wire.

Case II:(wire pointing East-West)

Here, the ends of the wire are pointed in perpendicular to the magnetic field of Earth, which is in north-south direction.
Hence, maximum flux is linked to the surface and emf is induced in the wire.