Question

If the horizontal component of the earth's magnetic field is $0.30G,$ and the dip angle is $60^{\circ }$ at a given place, then the value of earth's total magnetic field is

• A. $0.15G$
• B. $0.15\sqrt{3}G$
• C. $0.15\sqrt{2}G$
• D. $0.60G$

Answer 1

Answer: (D)

$B_H=0.30G$ Angle of dip $=60^{\circ }B=?$
Earths magnetic field is horizontal only at the magnetic equator.
At any other place, the total intensity can be resolved into horizontal component
$\left(B_H\right)$ and vertical component $\left(B_V\right)$
Also, $B_H=B\cos \varphi$ and $B_V=B\sin \varphi$
where, $\varphi$ is angle of inclination or dip
$\therefore 0.30=B\cos 60^{\circ }$
$0.30=\frac{B}{2}$
$\Rightarrow B=0.60G$