20.5.2—Φ = BA

When a uniform field is perpendicular to area A, magnetic flux simplifies to Φ=BA.

If the field is tilted, include cosθ; if the area or field varies, integrate or use a suitable average.

Doubling loop area doubles flux at fixed B, while rotating it edge-on reduces perpendicular flux toward zero.

The area is the surface enclosed by the loop, not the wire length.