In this example, we use Φ=BAcosϕ to solve for the strength of a magnetic field. A plane surface with area 2.2 cm2 is placed in a uniform magnetic field that is oriented at an angle of 30∘ to the surface. (a) What is the angle ϕ? (b) If the magnetic flux through this area is 0.60 mWb , what is the magnitude of the magnetic field?