Calculate the magnitude and angle

the second one and the forth one are in the purple because they are opinions and the rest are in the yellow

explanation:

this could be newton#'s law of cooling. the cooling curve is exponential

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.