The magnetic effect of electric current can be demonstrated by the following experiment. On an iron nail, wrap a copper wire in insulation, the ends of which are connected to a current source. When current flows, small iron objects are magnetized to the nail: paper clips, cloves, buttons, as soon as the chain breaks, the magnetic effect disappears, everything crumbles.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.