Which expression should appear in the blue box to compute percent error? accepted value – experimental value accepted value × experimental value experimental value + accepted value experimental value – accepted value

i don't understand. explain it clearly

option number c is the right 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.