What is use of compass?, |Why does a magnet attract iron?, |What effect strength of magnets?

Why does the compass needle always point to the north?

The earth have a huge magnetic field and all magnetic objects,such as the compass needle,get oriented to it.One end of the freely rotating compass needle marked in colour aligns itself with the north pole of the earth.This helped the early explorers to find their ways in oceans.Near the poles they often saw an impressive phenomenon in the sky known as aurora.Moreover,a lot of things would not have existed today without strong magnets called electromagnets that can be switched on and off.

Why does a magnet attract iron?

Magnet are made up of many tiny magnets,which are groups of iron atoms.Although these iron atoms are also present in non-magnetic metals,they are completely disorganized there.In contrast,in a permanent,in a permanent magnet,iron atoms are aligned in a uniform way.All the such poles point to one and and all the north poles to the other end.Thus,a magnet has a strong north pole and a strong south pole.If a piece of iron comes near a magnet,the atoms in it get aligned.The piece of iron becomes magnetized for short time and is attracted to one of the poles of the magnet.On removing the magnet,the alignment of the atoms gets disorganized again.In permanent magnets,atoms retain their alignment.

What effect strength of magnets?

Depending on the strength of the magnet,it attracts metallic pieces from different distances.Materials lying between the magnet and the metal affect its strength.A concrete slab interrupts the magnetic field of the magnet,whereas paper and skin do not.Even fake nose studs can hold through magnetic force.The magnetic field is made visible by laying a glass plate on a magnet and then scattering fine iron chips on it.The chips get aligned along the field lines,which run outside the magnet from the north pole to the south pole.