The magnetic flux through a coil is maximum when the plane of the coil is
- A. parallel to the field
- B. perpendicular to the field
- C. at 45 degrees to the field
- D. irrelevant to the flux
Explanation
Flux depends on the cosine of the angle between the field and the normal to the coil, so it is maximum when the normal points along the field, which means the plane of the coil is at right angles to it. When the plane contains the field lines, none of them thread the coil and the flux is zero. Rotating a coil between these extremes is what generates alternating current.