Question

In the absence of any current a compass needle rests in which direction (with respect to the earth)?
$\left( {\text{A}} \right)$ South-north
$\left( {\text{B}} \right)$ North-south
$\left( {\text{C}} \right)$ East-west
$\left( {\text{D}} \right)$ West-east

Answer 1

Hint: The earth is a giant magnet with a north and south magnetic field called the magnetosphere. Evidence poles switched positions hundreds of times in the past.

Complete step-by-step answer:
The earth acts like a huge magnet.
The Earth behaves like a magnet because the Earth is a magnet. It is not a static magnet, but an electromagnet. Deep within the Earth, molten metal (mostly iron) flows thanks to heat which causes convection.The Earth is a huge magnet.
The reason is that the world itself may be a huge "magnet". Earth's North Pole might be considered because of the south end of a magnet while Earth's South Pole might be considered because of the north end of a magnet. Thus, the north end of a compass needle is usually drawn towards the North Pole of the world.
The magnets rest in a north-south direction.
All magnets have two poles, the North Pole and the South Pole, and therefore the North Pole of 1 magnet is interested in the South Pole of another magnet and vice-versa. Therefore the compass needle when allowed to spin whichever way it wants, will always line itself along the north-south direction.
Thus within the absence of an electrical current, a compass needle always involves rest in Earth's North-south direction. However, when current passes through the circuit the needle rests within the direction opposite to the magnetic flux of Earth.
Hence it is South-North direction.

Option A is the correct answer.

Note: Compass show the north direction:
A compass points to the earth's magnetic poles, which aren't equivalent to the earth's geographic poles. When it comes to magnets, opposites attract. This fact means the north end of a magnet during a compass is interested in the south magnetic pole, which lies on the brink of the geographic North Pole.