Question

ASSERTION: The true geographic north direction is found by using a compass needle
REASON: The magnetic meridian of the earth is along the axis of rotation of the earth.
A) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B) Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C) Assertion is correct but Reason is incorrect
D) Both Assertion and Reason are incorrect

Answer 1

Hint: Freely suspended magnet carrying a specific direction called magnetic meridian and angle between geographical and magnetic meridian called angle of declination.

Complete answer:
As we know that a compass needle is magnetized and freely suspended to allow that horizontal force to pull it toward the magnetic north by some natural force. Moreover, the Earth's magnet is not perfectly arranged with the geographical north and south poles.
True geographic north direction is a difference between true north on a map and the north indicated by a compass that difference said to be the magnetic declination and it is measured by the angle between true north and magnetic north Moreover, the magnetic declinations vary from place to place and also depending on the intensity of the Earth's magnetic fields which is change yearly.

Hence, option (D) Both Assertion and Reason are incorrect.

Note: The intensity of the earth field is measured in gauss (G) and 1 G = ${10^6}nT$ and Intensity of the field is directly proportional to the force it exerted on a magnet.