Answer
In situation (b), the induced emf and the battery emf are in the same direction.
Work Step by Step
In situation (a), the battery emf is counterclockwise. Note that the flux out of the page is increasing. By Lenz's law, the induced current opposes this change. By the right hand rule, the induced current is in the clockwise direction. Therefore, the induced emf and the battery emf are in opposite directions.
In situation (b), the battery emf is clockwise. Note that the flux into the page is decreasing. By Lenz's law, the induced current opposes this change. By the right hand rule, the induced current is in the clockwise direction. Therefore, the induced emf and the battery emf are in the same direction.
In situation (c), the battery emf is clockwise. Note that the flux out of the page is decreasing. By Lenz's law, the induced current opposes this change. By the right hand rule, the induced current is in the counterclockwise direction. Therefore, the induced emf and the battery emf are in opposite directions.
In situation (b), the induced emf and the battery emf are in the same direction.
