The pressure in a fluid is affected by which characteristic of that fluid? A)The amount of hydrogen atoms in the fluid
B) The amount of oxygen atoms in the fluid
C) The weight of the fluid

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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.