Question

A dip circle, lying initially in the magnetic meridian is rotated through an angle $\theta$ in the horizontal plane, then the tangent of the angle of dip is increased in the ratio of :

• A. $1:\cos \theta$
• B. $1:\tan \theta$
• C. $1:\cot \theta$
• D. $1:\sin \theta$

Answer 1

The correct option is A $1:\cos \theta$

Let $\delta$ be the angle of dip when dip circle is in magnetic meridian
$\tan \delta =\frac{V}{H}$
The dip circle when makes an angle $\theta$ , horizontal component of the earth's magnetic field is $H\cos \theta$
The angle of dip when not in magnetic meridian is
$\tan {\delta }_1=\frac{V}{H\cos \theta }$
$\tan {\delta }_1=\frac{\tan \delta }{\cos \theta }$
$\frac{\tan {\delta }_1}{\tan \delta }=\frac{1}{\cos \theta }$