Q: A flux of 1 m Wb passes through a strip having an area A = 0.02 m2 . The plane of the strip is at an angle of 60º to the direction of a uniform field B . The value of B is
(A) 0.1 T
(B) 0.058 T
(C) 4.0 mT
(D) none of the above
Solution : Magnetic flux $\displaystyle \phi = B A cos\theta $
$\displaystyle 1 \times 10^{-3} = B (0.02) cos60^o $
B = 0.1 T