ANS:D - none of these

A venturi meter is a device used to measure the flow rate of fluid in a pipe. It operates on the principle of Bernoulli's equation and measures the differential pressure created by the fluid's velocity change as it passes through a constricted section of the meter. Therefore, a venturi meter primarily measures pressure. Here’s why:

• Principle of Operation: According to Bernoulli's equation, an increase in fluid velocity in a constricted area (throat) of the venturi meter results in a decrease in pressure. The difference in pressure between the upstream and throat sections of the meter is directly related to the velocity of the fluid.
• Measurement: By measuring the pressure difference between the upstream and throat sections of the venturi meter, the flow rate of the fluid can be determined. This pressure difference is a direct indication of the fluid velocity and hence the flow rate.
• Other Options:
  • Velocity head: This is related to the kinetic energy of the fluid due to its velocity and is indirectly related to the pressure difference measured by the venturi meter.
  • Point velocity: While the venturi meter indirectly measures fluid velocity through pressure difference, it does not directly measure point velocity.