question_answer

For an impulse turbine with exit angle '\[\phi \]', the maximum hydraulic efficiency is:

A) \[\left( 1-\frac{\cos \phi }{2} \right)\]                    

B) \[\left( \frac{1}{2}+\cos \phi  \right)\]

C) \[\left( \frac{1+\cos \phi }{2} \right)\]                   

D) \[\left( \frac{1-\cos \phi }{2} \right)\]