'विद्युत चुम्बक' किससे बनता है?

उत्तर: (D) तार की कुण्डली में विद्युत धारा प्रवाहित करके / By passing current through a coil of wire — An electromagnet is made by winding insulated wire around a soft iron core and passing electric current through it. It can be turned on/off and its strength can be controlled. Used in electric bells, ...