Question

a conductor is moving perpendicular to a variable magnetic field and the direction of magnetic field is reversing periodically then the polarity of induced emf across the conductor is​

Answer 1

Answer:

Reverses PERIODICALLLY.

Answer 2

This question is actually talking about Lenz effect.

In this case, the law suggests that if an induced electric current starts to flow in some direction and then the current constantly tries to oppose the change, then there will be a slight variation in which the current that is induced to flow will flow.

The direction or polarity of induced emf across the conductor will be judged accordingly.

Based on several factors, it will be decided  whether the conductor will flow in a clockwise direction or start to flow in an anti clockwise direction.