Question

In a plane perpendicular to the magnetic meridian the dip needle will remain :

• A. Vertical
• B. Horizontal
• C. At an angle of 45 from horizontal
• D. At an angle of 60 from vertical

Answer 1

The correct option is A Vertical

Earths magnetic South Pole is towards the earths North Pole, and magnetic North Pole is towards the geometrical South Pole. A magnetic needle is placed in the horizontal plane. It would align itself in the magnetic North-South (along the magnetic meridian).

There would be two vertical planes: One would pass through the magnetic meridian, and the other would be perpendicular to it. If the needle is placed in the vertical plane that passes through the magnetic meridian (at the equator) then the needle would show horizontal direction. If the needle is placed in horizontal plane at equator, then it would once again show horizontal direction. This is because there is only horizontal field there.If the needle is placed in the vertical plane (passing through magnetic meridian) at any point other than the equator and the poles, it would align in the direction of the resultant magnetic field.

Angle of dip would change if the needle is placed in geometric meridian. The vertical component would remain the same, but the horizontal component would change.

Hence, in a plane perpendicular to the magnetic meridian the dip needle will remain vertical.