Nozzle Shape and Pressure Decrease

You haven't told us the fluid...

http://en.wikipedia.org/wiki/Ludwieg_tube

This is as good a place as any to start.

http://en.wikipedia.org/wiki/Bernoulli%27s_principle

pressure just shows the resistant to flow.

think term "pressure" as back pressure.

if fluid have to flow through a 2" nozzle

and same flow has to flow through 1" nozzle, it will restrict the flowing fluid which increases the back pressure in line ..........

that much flow can pass through 2" nozzle that will gives less restriction to flow so there will be less back pressure as compared to 1"

same happens in diverging nozzle area increases and restriction to flow decreases hence pressure reduced

Velocity decreases (more area of crossection) so pressure will?

In diverging shape nozzle pressure decrese and velocity increse.

In converging shape nozzle pressure increase and velocity decrese.

is this right or wrong?

Your explanation is forcing me to ask a very basic question ,What is convergent?