MCQOPTIONS
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MCQOPTIONS
This section includes 95 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
*$_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 | |
| 52. |
*/*_Which of the following heating methods has maximum power factor?? |
| A. | Arc heating |
| B. | Dielectric heating |
| C. | Induction heating |
| D. | Resistance heating |
| Answer» E. | |
| 53. |
*/*_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 | |
| 54. |
*/*_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 | |
| 55. |
*/*_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 | |
| 56. |
*/*_Which of the following has the highest value of thermal conductivity?? |
| A. | Water |
| B. | Steam |
| C. | Solid ice |
| D. | Melting ice |
| Answer» D. Melting ice | |
| 57. |
*/*_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 | |
| 58. |
*/*_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 | |
| 59. |
*/*_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 | |
| 60. |
%_In induction heating __________ is abnormally high._% |
| A. | Phase angle |
| B. | Frequency |
| C. | Current |
| D. | Voltage |
| Answer» C. Current | |
| 61. |
_ 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 | |
| 62. |
_ In a domestic cake baking oven the temperature is controlled by$? |
| A. | Voltage variation |
| B. | Thermostat |
| C. | Autotransformer |
| D. | Series-parallel operation |
| Answer» E. | |
| 63. |
_ Which of the following devices is necessarily required for automatic temperature control in a furnace?$? |
| A. | Thermostat |
| B. | Thermocouple |
| C. | Autotransformer |
| D. | Heating elements of variable resistance material |
| Answer» C. Autotransformer | |
| 64. |
_ The process of heat transfer during the re-entry of satellites and missiles, at very high speeds, into earth?s atmosphere is known as$? |
| A. | Ablation |
| B. | Radiation |
| C. | Viscous dissipation |
| D. | Irradiation |
| Answer» B. Radiation | |
| 65. |
_ ________ has the highest value of thermal conductivity.$? |
| A. | Copper |
| B. | Aluminium |
| C. | Brass |
| D. | Steel |
| Answer» B. Aluminium | |
| 66. |
_ For radiant heating around 2250°C, the heating elements are made of$? |
| A. | Copper alloy |
| B. | Carbon |
| C. | Tungsten alloy |
| D. | Stainless steel alloy |
| Answer» D. Stainless steel alloy | |
| 67. |
_ In electric press, mica is used because it is _______ conductor of heat but/and________ conductor of electricity.$? |
| A. | bad, good |
| B. | bad, bad |
| C. | good, bad |
| D. | good, good |
| Answer» D. good, good | |
| 68. |
_ By the use of which of the following, high frequency power supply for induction furnaces can be obtained?$? |
| A. | Coreless transformers |
| B. | Current transformers |
| C. | Motor-generator set |
| D. | Multiphase transformer |
| Answer» D. Multiphase transformer | |
| 69. |
_The material of the heating element for a furnace should have$? |
| A. | Lower melting point |
| B. | Higher temperature coefficient |
| C. | High specific resistance |
| D. | All of the above |
| Answer» D. All of the above | |
| 70. |
A perfect black body is one that$? |
| A. | Transmits all incident radiations |
| B. | Absorbs all incident radiations |
| C. | Reflects all incident radiations |
| D. | Absorbs, reflects and transmits all incident radiations |
| Answer» C. Reflects all incident radiations | |
| 71. |
Which of the following is an advantage of heating by electricity?$? |
| A. | Quicker operation |
| B. | Higher efficiency |
| C. | Absence of flue gases |
| D. | All of the above |
| Answer» E. | |
| 72. |
________ is used for heating non-conducting materials.$? |
| A. | Eddy current heating |
| B. | Arc heating |
| C. | Induction heating |
| D. | Dielectric heating |
| Answer» E. | |
| 73. |
Method has leading power factor$? |
| A. | Resistance heating |
| B. | Dielectric heating |
| C. | Arc heating |
| D. | Induction heating |
| Answer» C. Arc heating | |
| 74. |
Induction heating takes place it which of the following?$? |
| A. | Insulating materials |
| B. | Conducting materials which are magnetic |
| C. | Conducting materials which are non-magnetic |
| D. | Conducting materials which may or may not be magnetic |
| Answer» E. | |
| 75. |
Heat is transferred simultaneously by condition, convection and radiation$? |
| 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 | |
| 76. |
Induction heating takes place in which of the following?$? |
| A. | Insulating materials |
| B. | Conducting materials which are magnetic |
| C. | Conducting materials which are nonmagnetic |
| D. | Conducting materials which may or may not be magnetic |
| Answer» E. | |
| 77. |
In a resistance furnace the atmosphere is$? |
| A. | Oxidizing |
| B. | Deoxidizing |
| C. | Reducing |
| D. | Neutral |
| Answer» B. Deoxidizing | |
| 78. |
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) | |
| 79. |
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. | |
| 80. |
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 taking place in the charge |
| D. | None of the above factors |
| Answer» D. None of the above factors | |
| 81. |
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. | Electromagnetic induction principle |
| Answer» E. | |
| 82. |
A non-dimensional number generally associated with natural convection heat transfer is |
| A. | Prandtl number |
| B. | Grashoff number |
| C. | Peclet number |
| D. | Nusselt number |
| Answer» C. Peclet number | |
| 83. |
In arc furnace the function of choke is |
| A. | To stabilize the arc |
| B. | To improve power factor |
| C. | To reduce severity of the surge |
| D. | None of the above |
| Answer» B. To improve power factor | |
| 84. |
Properly of low temperature coefficient 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) | |
| 85. |
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 | |
| 86. |
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 | |
| 87. |
Radiations from a black body are proportional to |
| A. | T |
| B. | T2 |
| C. | T3 |
| D. | T4 |
| Answer» E. | |
| 88. |
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 | |
| 89. |
Resistance variation method of temperature control is done by connecting resistance elements in |
| A. | Series |
| B. | Parallel |
| C. | Series-parallel connections |
| D. | All of the above ways |
| Answer» E. | |
| 90. |
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 | |
| 91. |
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 | |
| 92. |
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 | |
| 93. |
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 generated |
| C. | The area of the surface over which heat is produced can be accurately controlled |
| D. | All of the above |
| Answer» E. | |
| 94. |
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. | |
| 95. |
The electrode of a direct arc furnace is made of |
| A. | Tungsten |
| B. | Graphite |
| C. | Silver |
| D. | Copper |
| Answer» C. Silver | |