Which of the following correctly describe magnetic field lines?
check all that apply.
a. they begin on north poles and end on south poles.
b. they always cross.
c. field lines that are close together indicate a weaker magnetic
field.
d. they form complete loops.

The magnetic field lines start at a magnet's north pole and end at the south pole.

A. They begin on north poles and end on south poles.

Explanation:

Magnetic field lines are a visual instrument used to speak to attractive fields. They portray the bearing of the attractive power on a north monopole at some random position. The north post of one magnet draws in the south shaft however repulses the north shaft of another magnet dissimilar to shafts pull in and like shafts repulse.

A metal is a magnet on the off chance that it repulses a known magnet. Be that as it may, the Magnetic field lines don't simply end at the tip of the magnet. They go directly through it so that inside the magnet the attractive field focuses from the south shaft toward the north post.