JEE Main · 2021 · 22 Jul 2021 · Shift 2 · Magnetic Properties of Matter

In Earth's magnetism, when a dip circle is not in the magnetic meridian, it shows an apparent dip that is different from the true dip.

The relationship is: $\tan {\delta }_{\text{apparent}}=\frac{\tan {\delta }_{\text{true}}}{\cos \theta }$

where $\theta$ is the angle between the plane of the dip circle and the magnetic meridian.

Since $\cos \theta \le 1$, we have $\tan {\delta }_{\text{apparent}}\ge \tan {\delta }_{\text{true}}$

Therefore, the apparent dip is always greater than or equal to the true dip, which means the true dip is less than the apparent dip.