I have a physics question on

How the sensitivity of the manometer will change if a narrower tube is used for the manometer.

Logically speaking, it seems normal for the sensitivity of the manometer to increase with a decreasing diameter of the manometer.

However, if we use the formula $$ P=\frac{F}{a} $$

Assuming same pressure, if we decrease the diameter of the manometer, the area decreases and the force the gas acts on the liquid in the manometer decreases. In that sense, the sensitivity would decrease right.

I have no idea what the correct answer and explanation is. Please help!

  • $\begingroup$ Do you have a specific manometer in mind? The working principle will decide what answer is correct. For example, a membrane on a tube will be more rigid, as the tube is thinner. But a piston on a tube will be affected by the friction equally with the tube regardless of the internal diameter. $\endgroup$ – rmhleo Sep 26 '17 at 15:22
  • $\begingroup$ The manometer I'm thinking of is a liquid manometer. $\endgroup$ – Yiheng Zhao Sep 27 '17 at 6:31

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