Iron and steel are the substances most susceptible of this influence, but brass, nickel, and cobalt can also become magnets.
Does the magnetism imparted to a piece of soft iron, or steel, by contact with a natural magnet, remain permanent in their substances?
In the steel it does, but the soft iron loses its power as soon as it is removed from the magnet.
Is it necessary that absolute contact should take place between a magnet and a piece of soft iron to render the latter a magnet?
No, every piece of soft iron brought near a magnet becomes by induction itself a magnet.
What do you mean by induction?
It is the production of like effects in contiguous bodies. In electricity or magnetism, it is the influence exerted by an electrified or magnetized body through a non-conducting medium without any apparent communication of a current.
What is meant by the directive power of the magnet?
It is that power which will cause a magnet, when suspended freely, to constantly turn the same part towards the north pole and the opposite part towards the south pole of the earth.
What are the poles of a magnet?