21. A turbine is a device that converts

- Hydraulic energy into mechanical energy
- Mechanical energy into hydraulic energy
- Kinetic energy into mechanical energy
- Electrical energy into mechanical energy

22. The operating characteristic curves of a turbine are

- Varying speed curves
- Constant efficiency curves
- Constant head curves
- Constant speed curves

23. If the overall efficiency of a Pelton Turbine is 63% and its Mechanical efficiency is 80%, then its Hydraulic efficiency would be?

- 81.25%
- 55.25%
- 75.25%
- 85.25%

24. A Jet of water has a diameter of 0.3 cm. The absolute surface tension of water is 0.072 N/m and atmospheric pressure is 101.2 kN/m^{2}. The absolute pressure within the jet of water will be

- 101.104 kN/m
^{2} - 101.152 kN/m
^{2} - 101.248 kN/m
^{2} - 101.296 kN/m
^{2}

25. Cavitation in turbines affects turbines in the following ways except

- irregular collapse of vapour cavities
- vibration of turbine parts
- loss of turbine material
- reduction in efficiency of turbine
- excessive heating of water

26. Hydraulic efficiency of Francis turbine is

- directly proportional to velocity of whirl at inlet and inversely proportional to net head on turbine
- directly proportional to velocity of whirl at inlet and net head on turbine
- inversely proportional to velocity of whirl at inlet and net head on turbine
- inversely proportional to velocity of whirl at inlet and directly proportional to net head on turbine

27. A turbine develops 7225 kW power under a head of 25 m at 135 rpm. The specific speed of the turbine will be nearly

- 245
- 225
- 205
- 185

28. Which of the following statement is wrong?

- A Francis turbine is an impulse turbine
- The impulse turbine is generally fitted slightly above tail race
- The angle of taper on draft tube is less than 8°
- The reaction turbines are used for low head and high discharge.

29. A turbine develops 500 kW power under a head of 100 m at 252 r.p.m. What would be its normal speed under a head of 80m.

- 670 r.p.m.
- 250 r.p.m.
- 225 r.p.m.
- 550 r.p.m.

30. In Sardar Sarovar dam, around 80% of the total power is generated using

- Francis Turbine
- Kaplan Turbine
- Pelton Turbine
- Gravity Turbine