The discharge through a rectangular orifice is given by the expression as indicated below :

A

$$Q = \frac{2}{3} C_db\sqrt{2g}(H_2^{\frac{1}{2}} - H_1^{\frac{1}{2}})$$

B

$$Q = \frac{2}{3} C_db\sqrt{2g}(H_2^2 - H_1^2)$$

C

$$Q = \frac{2}{3} C_db\sqrt{2g}(H_2 - H_1)$$

D

$$Q = \frac{2}{3} C_db\sqrt{2g}(H_2^{\frac{3}{2}} - H_1^{\frac{3}{2}})$$