Explain briefly the single touch method.

The iron bar which is to be magnetised is kept on a table. A strong bar magnet is kept nearby and vertical with its pole touching one end of the bar to the other end. It is then raised and brought back to the starting point. The process is repeated about 30 to 40 times, moving the magnet always in the same direction. The bar is then turned upside down and treated similarly. The bar is tested by bringing it near some iron fillings. If the bar attracts the iron fillings, it shows that it has been magnetised. Thus, the iron bar becomes a magnet.