A metal sheet of cron has an area of 2cm? at a temperature of 15°C. if it is heated to a temperature of 85°C, what will be its final area at 85°C, what will be its final area at 85C7 (B=
2.4x10-51/co)

see earlier answer

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.