Question 36General Subjects - QMED

The correct answer is B) The float or rotor is more dense than the fluid being measured and is positioned so that the gravitational force down is balanced by the upward motion of the fluid flow. This is correct because in a variable area flow meter, such as a rotameter, the float or rotor is designed to be more dense than the fluid being measured. As the fluid flows upward through the tapered tube, the upward force of the fluid flow counteracts the downward gravitational force on the float, causing it to rise to a position where these forces are balanced. The position of the float or rotor within the tube indicates the flow rate of the fluid. The other options are incorrect because they describe a scenario where the float or rotor is less dense than the fluid, which is not the operating principle of a rotameter.