Q. The angle of the dip at a place is 40.6° and the vertical component of the earths magnetic field B_{V} = 6 × 10^{-5 } T. The total intensity of the earth’s magnetic field at this place is (sin 40.6° = 0.65)

(a) 7 × 10^{-5} T

(b) 6 × 10^{-5} T

(c) 5 × 10^{-5} T

(d) 9.2 × 10^{-5} T

Ans: (d)

Solution: $ \displaystyle B_v = B sin\theta $

$ \displaystyle B = \frac{B_v}{sin\theta} $

$ \displaystyle B = \frac{6\times 10^{-5}}{sin 40.6} $

$\displaystyle B = \frac{6\times 10^{-5}}{0.65} $

= 9.2 × 10^{-5} T