Explain magnetic declination.

(N/A) magnetic needle,which is free to swing horizontally,would lie in the magnetic meridian,and the north pole of the needle would point towards the magnetic north pole.
The angle between the north direction shown by a magnetic needle and the true north direction at any place is called the magnetic declination at that place.
Alternatively,the angle between the geographic meridian and the magnetic meridian at a place is called the magnetic declination.
The declination is larger at higher latitudes and smaller near the equator.
The declination in India is small,being $0^{\circ} 41^{\prime} E$ at Delhi and $0^{\circ} 58^{\prime} W$ at Mumbai. Thus,at both these places,a magnetic needle shows the true north quite accurately.