# Power Plant Questions and Answers – Kaplan, Francis and Deriaz Turbines – II

This set of Power Plant Multiple Choice Questions & Answers focuses on “Kaplan, Francis and Deriaz Turbines – II”.

1. The maximum number of jets, generally, employed in an impulse turbine without jet interference are __________
a) 2
b) 6
c) 7
d) 5

Explanation: The maximum number of jets, generally, employed in an impulse turbine without jet interference are 2.

2. A Francis turbine is used when the available head of water is?
a) 0 to 25 m
b) 25 to 250 m
c) > 250 m
d) none of the mentioned

Explanation: Francis Turbine is used for high heads of water.

3. The overall efficiency of a reaction turbine is the ratio of __________
a) actual work available at the turbine to the energy imparted to the wheel
b) power produced by the turbine to the energy actually supplied by the turbine
c) workdone on the wheel to the energy (or head of water) actually supplied to the turbine
d) none of the mentioned

Explanation: The overall efficiency of a reaction turbine is the ratio of power produced by the turbine to the energy actually supplied by the turbine.

4. Manometric head, in case of a centrifugal pump, is equal to __________
a) Suction lift + Loss of head in suction pipe due to friction + Delivery lift + Loss of head in delivery pipe due to friction + Velocity head in the delivery pipe
b) Energy per kN at outlet of impeller – Energy per kN at inlet of impeller
c) Workdone per kN of water – Losses within the impeller
d) All of the mentioned

Explanation: Manometric head, in case of a centrifugal pump = Suction lift + Loss of head in suction pipe due to friction + Delivery lift + Loss of head in delivery pipe due to friction + Velocity head in the delivery pipe = Energy per kN at outlet of impeller – Energy per kN at inlet of impeller = Workdone per kN of water – Losses within the impeller.

5. What is the mechanical efficiency of an impulse turbine?
a) ratio of the actual power produced by the turbine to the energy actually supplied by the turbine
b) ratio of the actual work available at the turbine to the energy imparted to the wheel
c) ratio of the Work done on the wheel to the energy of the jet
d) none of the mentioned

Explanation: The mechanical efficiency of an impulse turbine is ratio of the actual work available at the turbine to the energy imparted to the wheel.
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6. The speed of an imaginary turbine, identical with the given turbine, which will develop a unit power under a unit head, is known as?
a) unit speed
b) terrific speed
c) specific velocity
d) specific speed

Explanation: The speed of an imaginary turbine, identical with the given turbine, which will develop a unit power under a unit head, is known as Specific Speed.

7. Geometric similarity is said to exist between the model and the prototype if both of them __________
a) are equal in size and shape
b) have identical velocities
c) have identical forces
d) are identical in shape, but differ only in size

Explanation: Geometric similarity is said to exist between the model and the prototype, if both of them are identical in shape, but differ only in size.

8. A centrifugal pump will start delivering liquid only when the pressure rise in the impeller is equal to the __________

Explanation: A centrifugal pump will start delivering liquid only when the pressure rise in the impeller is equal to the manometric head.

9. Slip of a reciprocating pump is defined as the __________
a) sum of actual discharge and the theoretical discharge
b) ratio of actual discharge to the theoretical discharge
c) difference of theoretical discharge and the actual discharge
d) product of theoretical discharge and the actual discharge

Explanation: Slip of a reciprocating pump is defined as the difference of theoretical discharge and the actual discharge.

10. Multi-stage centrifugal pumps are used to __________
b) give high discharge
c) pump viscous fluids
d) all of the mentioned

Explanation: Multi-stage centrifugal pumps are used to produce high heads.

11. A hydraulic coupling belongs to the category of __________
a) power absorbing machines
b) energy transfer machines
c) power developing machines
d) energy generating machines

Explanation: A hydraulic coupling belongs to the category of energy transfer machines.

12. Discharge of a centrifugal pump is __________
a) inversely proportional to (diameter)2 of its impeller
b) inversely proportional to diameter of its impeller
c) directly proportional to (diameter)2 of its impeller
d) directly proportional to diameter of its impeller

Explanation: Discharge of a centrifugal pump is inversely proportional to (diameter)2 of its impeller.

13. Which of the following turbine is preferred for 0 to 25 m head of water?
a) Kaplan Turbine
b) Pelton Turbine
c) Francis Turbine
d) None of the mentioned

Explanation: Kaplan turbine is preferred for low heads of water.

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