Suppose that you determine the density of a mineral by measuring its mass (m) (4.635±0.002) g and its volume (1.13±0.05) ml. d = m/v what is the uncertainty in the computed density?

Explanation:

we have error in division of 2 quantities is related as

where are errors in quantities a,b

Thus error in density becomes

Applying values we get

thus

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.