Question

A dip circle is at right angle to the magnetic meridian. The apparent dip angle is
A. \[0\;^\circ \]
B. \[30\;^\circ \]
C. \[60\;^\circ \]
D. \[90\;^\circ \]

Answer 1

Hint: The above problem can be resolved using the magnetic meridian's concepts and applications and the dip angle. These concepts make sense when the mathematical formula for the apparent dip and angle with the magnetic meridian is applied. In the given problem, we are provided with the value of the angle made with the magnetic meridian. But we are supposed to find the values of apparent dip. Thus by applying the substitution of values in the equation, the desired result is obtained.

Complete step by step solution:
The mathematical relation between the apparent dip and angle with the magnetic meridian is,
\[\cot {\alpha _1} = \cot \alpha \times \cos {\alpha _2}\]
Here, \[{\alpha _1}\] is the apparent dip, \[{\alpha _2}\] is the angle made with the magnetic meridian and \[\alpha \]is the value of true dip.
As the dip circle is at right angle to the magnetic meridian. Then the value of the true dip will be 90 degrees.
Substituting the values in the above equation as,
\[\begin{array}{l}
\cot {\alpha _1} = \cot \alpha \times \cos {\alpha _2}\\
\Rightarrow \cot {\alpha _1} = \cot \alpha \times \cos 90\;^\circ \\
\Rightarrow \cot {\alpha _1} = 0\\
\Rightarrow {\alpha _1} = 90\;^\circ
\end{array}\]

Therefore, the apparent dip angle is of ninety degree and option (D) is correct.

Note: To resolve the given problem, one must understand the meaning of the magnetic meridian and its associated terms, including the true dip and the geographic meridian. The magnetic meridian refers to the projection of lines of force of the geomagnetic field of the surface of the earth. Moreover, the magnetic meridian of the earth is also known as the geomagnetic meridian, and the plane that passes through this point also connects the north and the south geomagnetic poles.