A red line represents the attractive force felt by the north pole of a bar magnet or compass needle held at the Earth's surface.
(A red line; represents; the attractive force felt by the north pole of a bar magnet or compass needle) (the attractive force; felt; by the north pole of a bar magnet or compass needle) (a bar magnet or compass needle; held; L:at the Earth's surface)
A red line the attractive force a bar magnet or compass needle
represents felt held
the attractive force felt by the north pole of a bar magnet or compass needle
by the north pole of a bar magnet or compass needle
L:at the Earth's surface