Angle of dip at a place is $$30^0 $$. If the vertical component of earth's magnetic field at that point is $$7.5\times 10^{-5}T$$. then the total magnetic field of earth at that point will be :
  • A
    $$7.5\times 10^{-5}T$$
  • B
    $$1.5\times 10^{-4}T$$
  • C
    $$8.67\times 10^{-5}T$$
  • D
    $$1.5\times 10^{-5}T$$

Solution

Vertical component of earth magnetic field:
$$B_v = B sin\theta$$
$$B= \dfrac{B_v}{sin\theta}= \dfrac{7.5\times 10^{-5} }{sin 30^0}= 2\times 7.5 \times 10^{-5}$$
$$= 1.5 \times 10^{-4}T$$