A manometer is a device used for what purpose?

• A. A device for measuring temperature with a liquid-filled strip.
• B. A device for measuring pressure with a liquid filled tube.
• C. A device for measuring electrical resistance.
• D. A device for measuring flow rate.

Answer: (B)

A manometer measures pressure by using a liquid-filled tube where the pressure difference on the two sides moves the liquid column. The height change of the liquid is directly related to the pressure difference (ΔP = ρ g Δh), so you read the pressure from how far the liquid rises or falls. Mercury or water can be used as the manometric liquid depending on the pressures involved, but the principle remains the same: a column of liquid provides a direct, measurable indicator of pressure. Other devices measure temperature, electrical resistance, or flow rate, which are not determined by a liquid column balancing against pressure, so they don’t describe what a manometer does.