my teacher today taught that when you bring an iron nail or any metal thing it get magnetized , but i think that if i took an iron bar and brought it near a bar magnet , if it were to be magnetized then it would  have poles so one end of iron bar should repel but this does not happen . why? and ?

We know that when an iron nail is brought close to a bar magnet, it attracts the bar magnet. This happens because the end of the nail acts as the opposite pole as that of the bar magnet and gets attracted.

This can be explained as, say the North pole of a bar magnet is brought close to the one end of an iron bar. The end of the iron bar will act as the South pole, due to which it gets attracted to the magnet and acts as a temporary magnet. When the magnet is moved away from the iron bar, it loses it magnetism and no longer acts a s a magnet.

It will get magnetized only when the bar magnet is rubbed for some time in one direction. By doing so, it acts as a magnet.