Question

A dip circle is so set that it moves freely in the magnetic meridian. In this position, the angle of dip is 40⁰. Now the dip circle is rotated so that the plane in which the needle moves makes an angle of 30⁰ with the magnetic meridian. In this position, the needle will dip by the angle

• A. 40⁰
• B. 30⁰
• C. More than 40⁰
• D. Less than 40⁰

Answer 1

Answer: (C)

More than 40⁰

Answer 2

By using $\tan \phi ^ { \prime } = \frac { \tan \phi } { \cos \beta }$; where$\phi = 40 ^ { \circ } , \beta = 30 ^ { \circ }$

As cos 30^o < 1 $\Rightarrow \frac { 1 } { \cos 30 ^ { \circ } } > 1$

Hence $\frac { \tan \phi ^ { \prime } } { \tan \phi } > 1 \Rightarrow \tan \phi ^ { \prime } > \tan \phi = \phi ^ { \prime } > \phi$ or