MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 146 Mcqs, each offering curated multiple-choice questions to sharpen your Power Systems knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Read the statements below. I. The built up rotor is cheaper and easier to manufacture. II. The high pressure and intermediate pressure rotors are always of integral type. |
| A. | Only statement I is correct |
| B. | Only statement II is correct |
| C. | I and II are correct |
| D. | I and II are wrong |
| Answer» D. I and II are wrong | |
| 2. |
The diagram efficiency is the ratio of |
| A. | workdone on the blades to the energy supplied to the blades |
| B. | workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam |
| C. | energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam |
| D. | none of the above |
| Answer» B. workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam | |
| 3. |
The critical pressure ratio for initially superheated steam is __________ as compared to initially dry saturated steam. |
| A. | more |
| B. | less |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 4. |
In an impulse turbine |
| A. | the steam is expanded in nozzles only and there is a pressure drop and heat drop |
| B. | the steam is expanded both in fixed and moving blades continuously |
| C. | the steam is expanded in moving blades only |
| D. | the pressure and temperature of steam remains constant |
| Answer» B. the steam is expanded both in fixed and moving blades continuously | |
| 5. |
The maximum efficiency of a De-Laval turbine is (where α = Nozzle angle) |
| A. | sin2 α |
| B. | cos² α |
| C. | tan2 α |
| D. | cot2 α |
| Answer» C. tan2 α | |
| 6. |
The pressure of steam, in reaction turbines, is reduced in the fixed blades as well as in moving blades. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 7. |
The compounding of turbines is done in order to |
| A. | reduce speed of rotor |
| B. | improve efficiency |
| C. | reduce exit losses |
| D. | all of these |
| Answer» E. | |
| 8. |
When the cross-section of a nozzle __________ continuously from entrance to exit, it is called a convergent nozzle. |
| A. | increases |
| B. | decreases |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 9. |
If the critical pressure ratio for steam is 0.546, then the steam is initially |
| A. | wet steam |
| B. | dry saturated steam |
| C. | superheated steam |
| D. | none of these |
| Answer» D. none of these | |
| 10. |
Rateau turbine is |
| A. | simple reaction turbine |
| B. | velocity compounded turbine |
| C. | pressure compounded turbine |
| D. | pressure-velocity compounded turbine |
| Answer» D. pressure-velocity compounded turbine | |
| 11. |
In a Parson's turbine stage, blade velocity is 320 m/s at the mean radius and rotor blade exit angle is 30°. For minimum kinetic energy of the steam leaving the stage, the steam velocity at the exit of the rotor will be |
| A. | 160/3 m/s |
| B. | 320/3 m/s |
| C. | 640/3 m/s |
| D. | 640 m/s |
| Answer» D. 640 m/s | |
| 12. |
The critical pressure ratio for gases is |
| A. | 0.528 |
| B. | 0.546 |
| C. | 0.577 |
| D. | 0.582 |
| Answer» B. 0.546 | |
| 13. |
In impulse turbines, when friction is neglected, the relative velocity of steam at outlet tip of the blade is __________ the relative velocity of steam at inlet tip of the blade. |
| A. | equal to |
| B. | less than |
| C. | greater than |
| D. | None of these |
| Answer» B. less than | |
| 14. |
The ratio of the cumulative heat drop to the isentropic heat drop is called reheat factor. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 15. |
When the inlet pressure of steam is equal to the exit pressure, then |
| A. | there is a pressure drop in the nozzle |
| B. | fluid flows through the nozzle |
| C. | pressure drops and fluid flows through the nozzle |
| D. | there is no pressure drop and fluid does not flow through the nozzle |
| Answer» E. | |
| 16. |
When the nozzle operates with the maximum mass flow, the nozzle is said to be |
| A. | choked |
| B. | underdamping |
| C. | overdamping |
| D. | none of these |
| Answer» B. underdamping | |
| 17. |
Reheating of steam in a turbine |
| A. | increases the workdone through the turbine |
| B. | increases the efficiency of the turbine |
| C. | reduces wear on the blades |
| D. | all of these |
| Answer» E. | |
| 18. |
A stage, in reaction turbine, is represented by |
| A. | number of casing |
| B. | number of entries of steam |
| C. | number of exits of steam |
| D. | each row of blades |
| Answer» E. | |
| 19. |
A nozzle is said to be a divergent nozzle |
| A. | when the cross-section of the nozzle increases continuously from entrance to exit |
| B. | when the cross-section of the nozzle decreases continuously from entrance to exit |
| C. | when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit |
| D. | none of the above |
| Answer» B. when the cross-section of the nozzle decreases continuously from entrance to exit | |
| 20. |
The effect of supersaturation is that the |
| A. | mass of the steam discharged increases |
| B. | entropy and specific volume of the steam increases |
| C. | exit velocity of steam reduces |
| D. | all of these |
| Answer» E. | |
| 21. |
The pressure of steam __________ while flowing through a nozzle. |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | None of these |
| Answer» C. remains constant | |
| 22. |
The friction present between the steam and the nozzle surfaces reduces the heat drop by |
| A. | 10 to 15 percent |
| B. | 15 to 25 percent |
| C. | 25 to 40 percent |
| D. | 40 to 60 percent |
| Answer» B. 15 to 25 percent | |
| 23. |
When the cross-section of a nozzle first increases from its entrance to throat, and then decreases from its throat to exit, it is not a convergent-divergent nozzle. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 24. |
For a Parson's reaction turbine, if α1 and α2 are fixed blade angles at inlet and exit respectively and β1 and β2 are the moving blade angles at entrance and exit respectively, then |
| A. | α1 = α2 and β1 = β2 |
| B. | α1 = β1 and α2 = β2 |
| C. | α1 < β1 and α2 > β2 |
| D. | α1 = β2 and β1 = α2 |
| Answer» E. | |
| 25. |
In an impulse turbine, steam expands |
| A. | wholly in blades |
| B. | wholly in nozzle |
| C. | partly in the nozzle and partly in blades |
| D. | none of these |
| Answer» C. partly in the nozzle and partly in blades | |
| 26. |
The process of maintaining the speed of the turbine constant for various load conditions, is known as |
| A. | bleeding |
| B. | reheating |
| C. | governing |
| D. | none of these |
| Answer» D. none of these | |
| 27. |
The density of supersaturated steam is about __________ that of the ordinary saturated vapour at the corresponding pressure. |
| A. | same as |
| B. | 2 times |
| C. | 4 times |
| D. | 8 times |
| Answer» E. | |
| 28. |
A steam nozzle converts |
| A. | heat energy of steam into kinetic energy |
| B. | kinetic energy into heat energy of steam |
| C. | heat energy of steam into potential energy |
| D. | potential energy into heat energy of steam |
| Answer» B. kinetic energy into heat energy of steam | |
| 29. |
In a reaction turbine |
| A. | the steam is allowed to expand in the nozzle, where it gives a high velocity before it enters the moving blades |
| B. | the expansion of steam takes place partly in the fixed blades and partly in the moving blades |
| C. | the steam is expanded from a high pressure to a condenser pressure in one or more nozzles |
| D. | the pressure and temperature of steam remains constant |
| Answer» C. the steam is expanded from a high pressure to a condenser pressure in one or more nozzles | |
| 30. |
The ratio of the isentropic heat drop to the heat supplied, is called |
| A. | reheat factor |
| B. | stage efficiency |
| C. | internal efficiency |
| D. | Rankine efficiency |
| Answer» E. | |
| 31. |
During flow through a nozzle, no heat is supplied or rejected by the steam. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 32. |
The friction in the nozzle __________ exit velocity of steam. |
| A. | has no effect on |
| B. | decreases |
| C. | increases |
| D. | None of these |
| Answer» C. increases | |
| 33. |
The velocity of steam, in reaction turbines, is increased in the fixed blades as well as in moving blades. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 34. |
In a De-Laval impulse turbine, the nozzle is kept very close to the blades. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 35. |
Blading efficiency is also known as |
| A. | stage efficiency |
| B. | diagram efficiency |
| C. | nozzle efficiency |
| D. | none of these |
| Answer» C. nozzle efficiency | |
| 36. |
The blade friction in the impulse turbine reduces the velocity of steam by __________ while it passes over the blades. |
| A. | 10 to 15% |
| B. | 15 to 20% |
| C. | 20 to 30% |
| D. | 30 to 40% |
| Answer» B. 15 to 20% | |
| 37. |
In a nozzle, whole frictional loss is assumed to occur between |
| A. | inlet and thoroat |
| B. | inlet and outlet |
| C. | throat and exit |
| D. | all of these |
| Answer» D. all of these | |
| 38. |
The rate of discharge through the nozzle __________ when the exit pressure is gradually reduced. |
| A. | remains same |
| B. | decreases |
| C. | increases |
| D. | None of these |
| Answer» D. None of these | |
| 39. |
The discharge of steam in a convergent-divergent nozzle __________ after the throat (i.e. in the divergent portion of the nozzle) |
| A. | remains constant |
| B. | decreases |
| C. | increases |
| D. | None of these |
| Answer» B. decreases | |
| 40. |
A nozzle is said to be a convergent nozzle |
| A. | when the cross-section of the nozzle increases continuously from entrance to exit |
| B. | when the cross-section of the nozzle decreases continuously from entrance to exit |
| C. | when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit |
| D. | none of the above |
| Answer» C. when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit | |
| 41. |
In order to reduce the rotor speed of an impulse turbine, the method employed is |
| A. | velocity compounding |
| B. | pressure compounding |
| C. | pressure-velocity compounding |
| D. | all of these |
| Answer» E. | |
| 42. |
In a reaction turbine when the degree of reaction is zero, then there is |
| A. | no heat drop in moving blades |
| B. | no heat drop in fixed blades |
| C. | maximum heat drop in moving blades |
| D. | maximum heat drop in fixed blades |
| Answer» B. no heat drop in fixed blades | |
| 43. |
The efficiency of a pressure-velocity compounded impulse turbine is __________ as compared to pressure compounded impulse turbine. |
| A. | same |
| B. | less |
| C. | more |
| D. | None of these |
| Answer» C. more | |
| 44. |
De-Laval turbines are mostly used |
| A. | where low speeds are required |
| B. | for small power purposes and low speeds |
| C. | for large power purposes |
| D. | for small power purposes and high speeds |
| Answer» E. | |
| 45. |
Which of the following statement is correct for steam turbines as compared to reciprocating steam engines? |
| A. | A steam turbine develops higher speeds |
| B. | The efficiency of steam turbine is higher |
| C. | The steam consumption is less |
| D. | all of these |
| Answer» E. | |
| 46. |
The ratio of total useful heat drop to the total isentropic heat drop, is called |
| A. | stage efficiency |
| B. | internal efficiency |
| C. | Rankine efficiency |
| D. | none of these |
| Answer» C. Rankine efficiency | |
| 47. |
The pressure velocity compounded impulse turbine allows a bigger pressure drop and hence __________ number of stages are required. |
| A. | more |
| B. | less |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 48. |
The expansion of steam, as it flows over the blades in reaction turbine, represents |
| A. | isothermal process |
| B. | isentropic process |
| C. | throttling process |
| D. | free-expansion process |
| Answer» C. throttling process | |
| 49. |
Parson's turbine is a |
| A. | simple impulse turbine |
| B. | simple reaction turbine |
| C. | impulse-reaction turbine |
| D. | none of these |
| Answer» C. impulse-reaction turbine | |
| 50. |
The ratio of the work delivered at the turbine shaft to the heat supplied is called overall thermal efficiency of turbine. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |