Question

A dip needle arranged to move freely in the magnetic meridian dips by an angle $\theta$. If the vertical plane in which the needle moves is rotated through an angle $\alpha$ to the magnetic meridian, then the needle will dip by an angle

• A. $\theta$
• B. $\alpha$
• C. more than $\theta$
• D. less than $\theta$

Answer 1

Answer: (C)

In this question, $\cos \alpha <1$
i.e., $\frac{1}{\cos \alpha }>1$
or, $\frac{\tan {\theta }^{\prime }}{\tan \theta }>1$
or, $\tan {\theta }^{\prime }>\tan \theta$
or, ${\theta }^{\prime }>\theta$
ie, angle of apparent dip is more than angle of actual dip $\theta$.