Imagine you have 1 kg each of iron, glass, and water, and all three samples are at 10°C. (a) Rank the samples from highest to lowest temperature after 100 J of energy is added to each sample.

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask

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.