What is the magnetic flux in the case when the plane of the contour is located along the lines of magnetic induction?

If the contour is oriented along the lines of magnetic induction, then the normal to the contour will be directed perpendicular to the lines of induction. The magnetic flux Ф is found by the formula:

Ф = B * Sк * cos a, where B is the absolute value of the induction vector, Sк is the area of the contour, a is the angle between the normal to the contour and the induction vector.

In our case, a = 90 ° and the factor cos a = cos 90 ° = 0, and therefore the product B * Sк * cos a is equal to zero.

Answer: Flow Ф = 0.