The magnetic field due to the earth is closely equivalent to that due to
A large magnet of length equal to the diameter of the earth
A magnetic dipole placed at the centre of the earth
A large coil carrying current
Neither of the above
At a place, the horizontal and vertical intensities of earth's magnetic field is $0.30$ Gauss and $0.173$ Gauss respectively. The angle of dip at this place is.....$^o$
The angle of dip is the angle
Lines which represent places of constant angle of dip are called
The lines joining the places of the same horizontal intensity are known as
Assertion : If a compass needle be kept at magnetic north pole of the earth the compass needle may stay in any direction.
Reason : Dip needle will stay vertical at the north pole of earth