Earth - a gigantic magnet - class-VIII

'Magnetic North' is a LOCATION, so-named to distinguish it from True North -it has NOTHING to do with its magnetic POLARITY. The magnetic polarity at this location is south -which is why it attracts the north-seeking pole of a compass needle or magnet.

Magnetic south pole of the Earth lies close to geographic north pole of the Earth.

Answer is D.

A freely suspended magnet always points in the North-South direction even in the absence of any other magnet. This suggests that the Earth itself behaves as a magnet which causes a freely suspended magnet (or magnetic needle) to point always in a particular direction: North and South. The shape of the Earth's magnetic field resembles that of a bar magnet of length one-fifth of the Earth's diameter buried at its center.
The South Pole of the Earth's magnet is in the geographical North because it attracts the North Pole of the suspended magnet and vice versa. Thus, there is a magnetic S-pole near the geographical North, and a magnetic N-pole near the geographical South. The positions of the Earth's magnetic poles are not well defined on the globe; they are spread over an area. The axis of Earth's magnet and the geographical axis do no coincide. The axis of the Earth's magnetic field is inclined at an angle of about 15 degrees with the geographical axis. Due to this a freely suspended magnet makes an angle of about 15 degrees with the geographical axis and points only approximately in the North-South directions at a place.

A freely suspended magnet always points in the North-South direction even in the absence of any other magnet. This suggests that the Earth itself behaves as a magnet which causes a freely suspended magnet (or magnetic needle) to point always in a particular direction: North and South.

In the Earth, the liquid metal that makes up the outer core passes through a magnetic field which causes an electric current to flow within the liquid metal. The electric current, in turn, creates its own  magnetic field—one that is stronger than the field that created it in the first place.

An iron rod buried inside earth along N-S direction becomes a weak magnet. It is only possible when the earth itself behaves like a magnet.

The magnetic meridian is an equivalent imaginary line connecting the magnetic south and north poles and can be taken as the magnetic force lines along the surface of the earth. Therefore a compass needle will be parallel to the magnetic meridian.

The angle between the magnetic and the true meridian is the angle of declination, which is relevant for navigating with a compass.

The field magnet used in a moving coil galvanometer is very strong. The earth's magnetic field is quite weak as compared to the magnetic field produced by the field magnet. Practically the coil rotates under the effect of the strong magnetic field due to the earth does not affect the working of the moving coil galvanometer.

The acceleration due to gravity at height h is given by g_h = g * R^2 / (R + h)^2. We are given that weight (and hence g_h) becomes 1/16 of the surface value, so g / 16 = g * R^2 / (R + h)^2. Taking the square root gives 1/4 = R / (R + h), which simplifies to R + h = 4R, so h = 3R.

The reason for the magnetic field of the earth is the magnetic substance in the earth’s core. 

So the pole of the earth is the pole of the magnetic substance in the earth’s core.

The actual north magnetic pole of earth is situated near the geographic south pole because the unlike poles attract each other.

As the material gets heated or it is in its liquid or gaseous state, the atoms or molecules are in rapid motion and are not aligned. Thus, fluids are seldom magnetic. An exception is when a magnetic material such as iron is in its liquid state and is continuously rotating around the axis; the atoms can be aligned in one direction, even though they are in liquid rapid motion.

Though two equal and opposite forces are acting on the needles, they don't cancel each other as they act on two different points and they generate torque which later at proper alignment reaches equilibrium such as

$\sum F=0$ and

$\sum M=0$

Angle of dip at a point on earth is the angle between earth's magnetic field at given point and the horizontal line of magnetic meridian.

Keep this well in mind that the magnetic poles are opposite in position as the geographic poles.

Due to motion of ions in earth's ionosphere the earth's magnetic field gets modified.