MCQOPTIONS
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MCQOPTIONS
This section includes 50 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Which of the following will happen if the thickness of refractory wall of furnace is increased ? |
| A. | Heat loss through furnace wall will increase |
| B. | Temperature inside the furnace will fall |
| C. | Temperature on the outer surface of furnace walls will drop |
| D. | Energy consumption will increase |
| Answer» D. Energy consumption will increase | |
| 2. |
Which of the following methods of heating is not dependent on the frequency of supply ? |
| A. | Induction heating |
| B. | Dielectric heating |
| C. | Electric resistance heating |
| D. | All of the above |
| Answer» D. All of the above | |
| 3. |
Which of the following methods is used to control temperature in resistance furnaces ? |
| A. | Variation of resistance |
| B. | Variation of voltage |
| C. | Periodical switching on and off of the supply |
| D. | All of the above methods |
| Answer» E. | |
| 4. |
Which of the following is an advantage of heating by electricity ? |
| A. | Quicker operation |
| B. | Higher efficiency |
| C. | Absence of flue gases |
| D. | All of the above |
| Answer» E. | |
| 5. |
Which of the following is an advantage of eddy current heating ? |
| A. | The amount of heat generated can be controlled accurately |
| B. | Heat at very high rate can be gene-rated |
| C. | The area of the surface over which heat is produced can be accurately controlled |
| D. | All of the above |
| Answer» E. | |
| 6. |
Which of the following insulating materials was suitable for low temperature applications ? |
| A. | Asbestos paper |
| B. | Diatomaceous earth |
| C. | 80 percent magnesia |
| D. | Cork |
| Answer» C. 80 percent magnesia | |
| 7. |
Which of the following heating methods has maximum power factor ? |
| A. | Arc heating |
| B. | Dielectric heating |
| C. | Induction heating |
| D. | Resistance heating |
| Answer» E. | |
| 8. |
Which of the following has the highest value of thermal conductivity ? |
| A. | Water |
| B. | Steam |
| C. | Sold ice |
| D. | Melting ice |
| Answer» D. Melting ice | |
| 9. |
Which of the following devices is necessarily required for automatic temperature control in a furnace ? |
| A. | Thermostat |
| B. | Thermocouple |
| C. | Auto-transformer |
| D. | Heating elements of variable resis-tance material |
| Answer» C. Auto-transformer | |
| 10. |
When a body reflects entire radiation incident on it, then it is known as____________? |
| A. | white body |
| B. | grey body |
| C. | black body |
| D. | transparent body |
| Answer» B. grey body | |
| 11. |
The temperature inside a furnace is usually measured by which of the following ? |
| A. | Optical pyrometer |
| B. | Mercury thermometer |
| C. | Alcohol thermometer |
| D. | Any of the above |
| Answer» B. Mercury thermometer | |
| 12. |
The process of heat transfer during the reentry of satellites and missiles, at very high speeds, into earth’s atmosphere is known as_______________? |
| A. | ablation |
| B. | radiation |
| C. | viscous dissipation |
| D. | irradiation |
| Answer» B. radiation | |
| 13. |
The material of the heating element for a furnace should have___________? |
| A. | lower melting point |
| B. | higher temperature coefficient |
| C. | high specific resistance |
| D. | all of the above |
| Answer» D. all of the above | |
| 14. |
The electrode of a direct arc furnace is made of____________? |
| A. | tungsten |
| B. | graphite |
| C. | silver |
| D. | copper |
| Answer» C. silver | |
| 15. |
Resistance variation method of temperature control is done by connecting resistance elements in_____________? |
| A. | series |
| B. | parallel |
| C. | series-parallel connections |
| D. | star-delta connections |
| E. | all of the above ways |
| Answer» F. | |
| 16. |
Radiations from a black body are proportional to____________? |
| A. | T1 |
| B. | T2 |
| C. | T3 |
| D. | T* |
| Answer» E. | |
| 17. |
Radiant heating is used for which of the following ? |
| A. | Annealing of metals |
| B. | Melting of ferrous metals |
| C. | Heating of liquids in electric kettle |
| D. | Drying of paints and varnishes |
| Answer» E. | |
| 18. |
Properly of low temperature co-eflficient of heating element is desired due to which of the following reasons ? |
| A. | To avoid initial rush of current |
| B. | To avoid change in kW rating with temperature |
| C. | Both (A) and (B) |
| D. | Either (A) or (B) |
| Answer» D. Either (A) or (B) | |
| 19. |
method has leading power factor____________? |
| A. | Resistance heating |
| B. | Dielectric heating |
| C. | Arc heating |
| D. | Induction heating |
| Answer» C. Arc heating | |
| 20. |
It is desirable to operate the arc furnaces at power factor of_____________? |
| A. | zero |
| B. | 0.707 lagging |
| C. | unity |
| D. | 0.707 leading |
| Answer» C. unity | |
| 21. |
is used for heating non-conducting materials? |
| A. | Eddy current heating |
| B. | Arc heating |
| C. | Induction heating |
| D. | Dielectric heating |
| Answer» E. | |
| 22. |
Induction heating process is based on which of the following principles ? |
| A. | Thermal ion release principle |
| B. | Nucleate heating principle |
| C. | Resistance heating principle |
| D. | Electro-magnetic induction princi¬ple |
| Answer» E. | |
| 23. |
Induction heating takes place it which of the following ? |
| A. | Insulating materials |
| B. | Conducting materials which are magnetic |
| C. | Conducting materials which are non-magnetic |
| D. | Conducting materials which may or may not be magnetic |
| Answer» E. | |
| 24. |
Induction furnaces are employed for which of the following ? |
| A. | Heat treatment of castings |
| B. | Heating of insulators |
| C. | Melting aluminium |
| D. | None of the above |
| Answer» B. Heating of insulators | |
| 25. |
In the indirect resistance heating method, maximum heat-transfer takes place by____________? |
| A. | radiation |
| B. | convection |
| C. | conduction |
| D. | any of the above |
| Answer» B. convection | |
| 26. |
In resistance heating highest working temperature is obtained from heating elements made of_____________? |
| A. | nickel copper |
| B. | nichrome |
| C. | silicon carbide |
| D. | silver |
| Answer» D. silver | |
| 27. |
In induction heating ___________ is abnormally high? |
| A. | phase angle |
| B. | frequency |
| C. | current |
| D. | voltage |
| Answer» C. current | |
| 28. |
In heating the ferromagnetic material by induction heating, heat is produced due to_____________? |
| A. | induced current flow through the charge |
| B. | hysteresis loss taking place below curie temperature |
| C. | due to hysteresis loss as well as eddy current loss takingplace in the charge |
| D. | none of the above factors |
| Answer» D. none of the above factors | |
| 29. |
In electric press, mica is used because it is _________ conductor of heat but/and __________ conductor of electricity? |
| A. | bad, good |
| B. | bad, bad |
| C. | good, bad |
| D. | good, good |
| Answer» D. good, good | |
| 30. |
In direct arc furnace, which of the following has high value ? |
| A. | Current |
| B. | Voltage |
| C. | Power factor |
| D. | All of the above |
| Answer» B. Voltage | |
| 31. |
In arc furnace the function of choke is______________? |
| A. | to stabilize the arc |
| B. | to imprpve, power factor |
| C. | to reduce severity of the surge |
| D. | none of the above |
| Answer» B. to imprpve, power factor | |
| 32. |
In an electric room heat convector the method of heating used is______________? |
| A. | arc heating |
| B. | resistance heating |
| C. | induction heating |
| D. | dielectric heating |
| Answer» C. induction heating | |
| 33. |
In an electric press mica is used_____________? |
| A. | as an insulator |
| B. | as a device for power factor improvement |
| C. | for dielectric heating |
| D. | for induction heating |
| Answer» B. as a device for power factor improvement | |
| 34. |
In a resistance furnace the atmosphere is_____________? |
| A. | oxidizing |
| B. | deoxidising |
| C. | reducing |
| D. | neutral |
| Answer» B. deoxidising | |
| 35. |
In a domestic cake baking oven the temperature is controlled by________________? |
| A. | voltage variation |
| B. | thermostat |
| C. | auto-transformer |
| D. | series-parallel operation |
| Answer» E. | |
| 36. |
Hysteresis loss and eddy current loss are used in____________? |
| A. | induction heating of steel |
| B. | dielectric heating |
| C. | induction heating of brass |
| D. | resistance heating |
| Answer» B. dielectric heating | |
| 37. |
Heat transfer by condition will not occur when____________? |
| A. | bodies are kept in vacuum |
| B. | bodies are immersed in water |
| C. | bodies are exposed to thermal radiations |
| D. | temperatures of the two bodies are identical |
| Answer» E. | |
| 38. |
Heat is transferred simultaneously by condition, convection and radiation_____________? |
| A. | inside boiler furnaces |
| B. | during melting of ice |
| C. | through the surface of the insulted pipe carrying steam |
| D. | from refrigerator coils to freezer of a refrigerator |
| Answer» B. during melting of ice | |
| 39. |
_________ has the highest value of thermal conductivity? |
| A. | Copper |
| B. | Aluminium |
| C. | Brass |
| D. | Steel |
| Answer» B. Aluminium | |
| 40. |
For the transmission of heat from one body to another__________? |
| A. | temperature of the two bodies must be different |
| B. | both bodies must be solids |
| C. | both bodies must be in contact |
| D. | at least one of the bodies must have some source of heating |
| Answer» B. both bodies must be solids | |
| 41. |
For radiant heating around 2250°C, the heating elements are made of____________? |
| A. | copper alloy |
| B. | carbon |
| C. | tungsten alloy |
| D. | stainless steel alloy |
| Answer» D. stainless steel alloy | |
| 42. |
For intermittent work which of the following furnaces is suitable ? |
| A. | Indirect arc furnace |
| B. | Core less furnace |
| C. | Either of the above |
| D. | None of the above |
| Answer» D. None of the above | |
| 43. |
For heating element high resistivity material is chosen to______________? |
| A. | reduce the length of heating element |
| B. | increase the life of the heating element |
| C. | reduce the effect of oxidation |
| D. | produce large amount of heat |
| Answer» B. increase the life of the heating element | |
| 44. |
Due to which of the following reasons it is desirable to have short arc length ? |
| A. | To achieve better heating |
| B. | To increase the life of roof refractory |
| C. | To have better stirring action |
| D. | To reduce problem of oxidation |
| E. | All of the above |
| Answer» F. | |
| 45. |
Direct arc furnaces have which of the following power factors ? |
| A. | Unity |
| B. | Low, lagging |
| C. | Low, leading |
| D. | Any of the above |
| Answer» C. Low, leading | |
| 46. |
By which of the following methods the temperature inside arc nace can be varied ? |
| A. | By disconnecting some of the heating elements |
| B. | By varying the operating voltage |
| C. | By varying the current through heating elements |
| D. | By any of the above method |
| Answer» E. | |
| 47. |
By the use of which of the following, high frequency power supply for induction furnaces can be obtained ? |
| A. | Coreless transformers |
| B. | Current transformers |
| C. | Motor-generator set |
| D. | Multi-phase transformer |
| Answer» D. Multi-phase transformer | |
| 48. |
Ajax Wyatt furnace is started when____________? |
| A. | it is filled below core level |
| B. | it is filled above core level |
| C. | it is fully empty |
| D. | none of the above |
| Answer» C. it is fully empty | |
| 49. |
A perfect black body is one that_____________? |
| A. | transmits all incident radiations |
| B. | absorbs all incident radiations |
| C. | reflects all incident radiations |
| D. | absorbs, reflects and transmits all incident radiations |
| Answer» C. reflects all incident radiations | |
| 50. |
A non-dimensional number generally associated with natural convection heat transfer is____________? |
| A. | Prandtl number |
| B. | Grashoff number |
| C. | Pecelet number |
| D. | Nusselt number |
| Answer» C. Pecelet number | |