A dip circle is taken to geomagnetic equator. The needle is allowed to move in a vertical plane perpendicular to the magnetic meridian. The needle will stay

Options

A. At an angle `30^@` with the horizontal
B. At an angle `45^@` with the vertical
C. Vertical
D. Horizontal

Answer

C

Explanation

If plane of rotation of magnetic needle is perpendicular to the magnetic meridian then it means horizontal component of Earth.s magnetic field is perpendicular to its plane and hence cannot apply torque on the needle. Only vertical component of earth.s magnetic field lies in the plane of dip circle and hence needle will become purely vertical in this case.