Question

The value of the horizontal component of the earth's magnetic field and angle of dip are $1.8\times {10}^{-5}Weber/m^2$ and ${30}^0$ respectively at some place. The total intensity of earth's magnetic field at that place will be

• A. $3.18\times {10}^{-5}Weber/m^2$
• B. $3.67\times {10}^{-5}Weber/m^2$
• C. $5.0\times {10}^{-5}Weber/m^2$
• D. $2.08\times {10}^{-5}Weber/m^2$
  

Answer 1

The correct option is D $2.08\times {10}^{-5}Weber/m^2$


IMAGE

Let $B_H$ and $B$ be horizontal component and total intensity of magnetic field of earth
$\Rightarrow B_H=Bcos\varphi$
$\Rightarrow B=\frac{B_H}{cos\varphi }$

$=\frac{1.8\times {10}^{-5}Weber/m^2}{\frac{\sqrt{3}}{2}}$

$=2.08\times {10}^{-5}Weber/m^2$

Hence, correct option is $\left(a\right)$.