Suppose this page is perpendicular to B and magnetic flux through it is 5 wb. If the pg is turned 30 degrees around an edge, flux through it will be:

Question

Suppose this page is perpendicular to a uniform magnetic field and the magnetic flux through it is 5 wb. If the page is turned by 30 degrees around an edge the flux through it will be:
1. 5.0 wb
2. 4.3 wb
3. 10.0 wb
4. 2.5 wb
5. 5.8 wb

Answer 1

Magnetic flux = Φ₀ = 5 Wb
The page is turned around through an angle = 30° 
Thus, magnetic through the edge of the paper is 
Φ_B = Φ₀ cosθ = 5 cos 30° = 5 x 0.866 = 4.33 Wb