Explain geographic meridian and magnetic meridian.

(N/A) $(i)$ Geographic meridian: Consider a point on the Earth's surface. At such a point,the direction of the longitude circle determines the geographic north-south direction,where the line of longitude towards the geographic North Pole represents the direction of true north.
Definition: The vertical plane passing through the geographic North and South Poles and the axis of rotation of the Earth is called the geographic meridian.
$(ii)$ Magnetic meridian: The vertical plane at any place on the Earth that passes through the imaginary line joining the magnetic North and South Poles is called the magnetic meridian.