Question

At a certain place the angle of dip is ${30}^{\circ }$ and the horizontal component of earth's magnetic field is $0.50\text{Oe}$. The earth's total magnetic field is (in Oestred)

• A. $\sqrt{3}$
• B. $1$
• C. $\frac{1}{\sqrt{3}}$
• D. $\frac{1}{2}$

Answer 1

The correct option is C $\frac{1}{\sqrt{3}}$

Given, $B_H=0.5\text{Oe};\theta ={30}^{\circ }$

The horizontal component of earth's magnetic field is,

$B_H=B\cos \theta$

$\therefore B=\frac{B_H}{\cos \theta }=\frac{0.5}{\cos {30}^o}=\frac{0.5}{\frac{\sqrt{3}}{2}}=\frac{1}{\sqrt{3}}\text{Oe}$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(C\right)$ is the correct answer.