What is Venturimeter.State the principle of its working,Derive an expression to find the rate of liquid flowing through a pipe

A Venturi Meter works on the principle of the Venturi Effect which is the pressure difference that occurs when the fluid velocity changes. Consider the figure below.

The velocity of the fluid at point 1 is less compared to the velocity at point 2, according to the equation of continuity. Now, by looking at the fluid levels in the vertical tubes we can say that the pressure exerted by the fluid at 1 is thus greater than exerted at point 2. The level difference of the fluid in the tubes is denoted by 'h'.

This means that the pressure exerted by a fluid in motion is inversely proportional to its velocity.