ANS:C - longer than convergent cone

In a venturi meter, the divergent cone is typically kept longer than the convergent cone. A venturi meter consists of a convergent section followed by a divergent section. The convergent section narrows down the flow, increasing its velocity, while the divergent section gradually expands, reducing the velocity and recovering some of the pressure energy. The divergent section, being longer than the convergent section, allows for a gradual expansion of the flow and helps in recovering pressure and reducing losses caused by the contraction in the convergent section. This design helps in minimizing head loss and providing accurate flow measurements. Therefore, the correct option is: longer than the convergent cone.