21. Low discharges are effectively measured by

1. Rectangular notch
2. Stepped notch
3. Trapezoidal notch
4. Triangular notch

22. The ratio of the percentage error in the discharge and percentage error in the measurement of head over a triangular notch is

1. 2/3
2. 2/5
3. 5/2
4. 3/2

23. A triangular notch is preferred to a rectangular notch because

1. only one reading is required
2. its formula is simple to remember
3. it gives more accurate results for low discharge
4. it measures a wide range of flows accurately
5. all of the above options

24. If the coefficient of discharge is 0.6, then the discharge over a right angled notch is

1. 1.417 H^5/2
2. 0.417 H^5/2
3. 7.141 H^5/2
4. 4.171 H^5/2

25. The discharged over a triangular notch depends on the central angle of the notch, head over the notch, acceleration due to gravity and kinematics viscosity of the fluid. The number of non-dimensional terms formed for the phenomenon is

1. 4
2. 3
3. 2
4. 1