Comparison Between Cut-Throat and Parshall Flumes (Skogerboe et al., 1973):

• Statement (A) is True: The cut-throat flume was developed specifically by removing the parallel throat section of the Parshall flume, connecting the converging inlet section directly to the diverging exit section over a flat horizontal floor.
• Statement (B) is True: Under free-flow conditions, cut-throat flumes provide discharge measurement accuracy comparable to standard Parshall flumes (within $2 - 5\%$ error).
• Statement (C) is False: In cut-throat flumes, the geometry is standardized such that the angle of convergence ($3:1$) and angle of divergence ($6:1$) remain CONSTANT across all flume sizes; only the throat width and overall length vary.
• Statement (D) is True: Having a completely flat bottom without the depressed floor of a Parshall throat makes cut-throat flumes significantly simpler and cheaper to fabricate and install in irrigation channels.

Condition for Maximum Efficiency in a DC Shunt Machine:

• Power Loss Balance: In a DC shunt generator or motor, total losses comprise constant iron, mechanical, and shunt field losses ($P_i$ or $P_c$) and variable armature copper losses ($I_a^2 R_a$).
• Maximum Efficiency Condition: Efficiency is maximized when the variable loss equals the constant loss:
  $$I_a^2 R_a = P_i$$
• Solving for Armature Current ($I_a$):
  $$I_a^2 = \frac{P_i}{R_a} \implies I_a = \sqrt{\frac{P_i}{R_a}}$$
  where $P_i$ is constant loss and $R_a$ is armature circuit resistance.