Question

The needle of the dip circle of a place stay at ${30}^0$. The dip circle is inclined at an angle towards ${30}^0$ with the magnetic meridian . The true dip at the place is:

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

Answer 1

Answer: (C)

${\tan }^{-1}\frac{1}{2}$

Formula for true dip is,
$\tan \delta =\tan {\delta }^{\prime }\cos \alpha$
$=\tan {30}^0\cos {30}^0$
$=\frac{1}{\sqrt{3}}\frac{\sqrt{3}}{2}=\frac{1}{2}$

$\Rightarrow \delta ={\tan }^{-1}\frac{1}{2}$