Q.Define the three magnetic elements of the Earth at a place -- the angle of declination, the angle of dip (inclination), and the horizontal component of the Earth's magnetic field -- and write the relation connecting the dip angle to the horizontal and vertical components.

Declination $D$: the horizontal angle between the geographic meridian (true north-south) and the magnetic meridian (the plane a compass needle settles in) at a given place.

Angle of dip $\delta$ (inclination): the angle the Earth's total field vector $\vec{B}_E$ makes with the horizontal, in the magnetic meridian plane; a dip needle (free to rotate about a horizontal axis) settles along this tilted direction.

Horizontal component $H$: the component of $\vec{B}_E$ lying in the horizontal plane, along the magnetic meridian -- the part an ordinary compass needle aligns with. …

Define each element in words first, then give the right-triangle relation connecting dip to …

• Confusing declination (a horizontal-plane angle, between two compass directions) with dip (a vertical-plan …