The specific speed ($$N_S$$) of a centrifugal pump is given by

A

$$\frac{N\sqrt{Q}}{H^{\frac{2}{3}}}$$

B

$$\frac{N\sqrt{Q}}{H^{\frac{3}{4}}}$$

C

$$\frac{N\sqrt{Q}}{H}$$

D

$$\frac{N\sqrt{Q}}{H^{\frac{5}{4}}}$$