Electrical Heating Objective Questions and Answers

In this article, we shared the electrical heating objective questions and answers for electrical and electronics engineers.

Electrical Heating Objective Questions

Electrical Heating Objective Questions and Answers

The below list provides all the multiple-choice questions related to electrical heating.

Answers are available at the bottom of the article.

1. Which of the following methods is used to control the temperature in resistance furnaces?

A)Variation of resistance
B)Variation of voltage
C)All of these answers
D)Periodical switching on and off of the supply

2. ____ has the highest value of thermal conductivity.


3. When a body reflects the entire radiation incident on it, then it is known as

A)grey body
B)white body
C)black body
D)transparent body

4. In the indirect resistance heating method, maximum heat transfer takes place by

C)any of these answers

5. Radiations from proportional to a black body are


6. Which of the following methods of heating is not dependent on the frequency of supply?

A)Dielectric heating
B)Induction heating
C)All of these answers
D)Electric resistance heating

7. For intermittent work which of the following furnaces is suitable?

A)None of these answers
B)Either Electrical Welding or Electrical Welding
C)Electrical Welding
D)Electrical Welding

8. In heating the ferromagnetic material by induction heating, heat is produced due to

A)induced current flow through the charge
B)due to hysteresis loss as well as eddy current loss taking place in the charge
C)none of these answers
D)hysteresis loss taking place below curie temperature

9. ____ is used for heating non-conducting materials.

A)Arc heating
B)Induction heating
C)Eddy current heating
D)Dielectric heating

10. In direct arc furnace, which of the following has high value?

B)Power factor
C)All of these answers

11. Heat transfer by the condition will not occur when

A)bodies are kept in a vacuum
B)bodies are exposed to thermal radiations
C)bodies are immersed in water
D)temperatures of the two bodies are identical

12. Hysteresis loss and eddy current loss are used in

A)resistance heating
B)induction heating of steel
C)induction heating of brass
D)dielectric heating

13. The temperature inside a furnace is usually measured by which of the following?

A)Mercury thermometer
B)Any of these answers
C)Alcohol thermometer
D)Optical pyrometer

14. In resistance heating, highest working temperature is obtained from heating elements made of ____

C)nickel copper
D)silicon carbide

15. Radiant heating is used for which of the following?

A)Heating of liquids in an electric kettle
B)Melting of ferrous metals
C)Annealing of metals
D)Drying of paints and varnishes

16. ____ method has a leading power factor

A)Resistance heating
B)Arc heating
C)Dielectric heating
D)Induction heating

17. In a domestic cake baking oven the temperature is controlled by

A)series-parallel operation
C)voltage variation

18. By the use of which of the following, high-frequency power supply for induction furnaces can be obtained?

A)Coreless transformers
B)Motor-generator set
C)Multi-phase transformer
D)Current transformers

19. Induction furnaces are employed for which of the following?

A)Heating of insulators
B)Heat treatment of castings
C)None of these answers
D)Melting aluminium

20. 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 principle

21. By which of the following methods the temperature inside a resistance furnace can be varied?

A)By disconnecting some of the heating elements
B)By varying the current through heating elements
C)By varying the operating voltage
D)any of these answers

22. For radiant heating around 2250°C, the heating elements are made of

A)tungsten alloy
B)copper alloy
C)stainless steel alloy

23. The material of the heating element for a furnace should have

A)all of these answers
B)higher temperature co-efficient
C)lower melting point
D)high specific resistance

24. 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

25. For heating element high resistivity material is chosen to

A)reduce the effect of oxidation
B)increase the life of the heating element
C)produce large amount of heat
D)reduce the length of heating element

26. Property of low-temperature co-efficient of the heating element is desired due to which of the following reasons?

A)To avoid change in kW rating with temperature
B)Both To avoid initial rush of current and To avoid change in kW rating with temperature
C)To avoid initial rush of current
D)Either To avoid initial rush of current or To avoid change in kW rating with temperature

27. In an electric room heat convector the method of heating used is

A)arc heating
B)resistance heating
C)induction heating
D)dielectric heating

28. In arc furnace, the function of the choke is

A)none of these answers
B)to stabilize the arc
C)to reduce severity of the surge
D)to improve power factor

29. Which of the following insulating materials is suitable for low-temperature applications?

A)Asbestos paper
C)80 percent magnesia
D)Diatomaceous earth

30. Induction heating takes place in which of the following?

A)Conducting materials which may or may not be magnetic
B)Insulating materials
C)Conducting materials which are magnetic
D)Conducting materials which are non-magnetic

31. Heat is transferred simultaneously by condition, convection, and radiation

A)inside boiler furnaces
B)through the surface of the insulted pipe carrying steam
C)from refrigerator coils to freezer of a refrigerator
D)during melting of ice

32. The electrode of a direct arc furnace is made of


33. In a resistance furnace the atmosphere is ____


34. A perfect black body is one that

A)transmits all incident radiations
B)reflects all incident radiations
C)absorbs, reflects and transmits all incident radiations
D)absorbs all incident radiations

35. Which of the following is an advantage of eddy current heating?

A)Heat at very high rate can be generated
B)The amount of heat generated can be controlled accurately
C)The area of the surface over which heat is produced can be accurately controlled
D)All of these answers

36. For the transmission of heat from one body to another

A)both bodies must be solids
B)at least one of the bodies must have some source of heating
C)the temperature of the two bodies must be different
D)both bodies must be in contact

37. Which of the following heating methods has maximum power factor?

A)Resistance heating
B)Dielectric heating
C)Arc heating
D)Induction heating

38. In induction heating ____ is abnormally high.

B)phase angle

39. Resistance variation method of temperature control is done by connecting resistance elements in

C)all of these answers
D)series-parallel connections
E)star-delta connections

40. Direct arc furnaces have which of the following power factors?

A)Low, lagging
B)Any of these answers
D)Low, leading

41. 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 reduce problem of oxidation
D)All of these answers
E)To have better stirring action

42. Which of the following has the highest value of thermal conductivity?

B)Melting ice
C)Solid ice

43. Ajax Wyatt furnace is started when

A)it is fully empty
B)it is filled below core level
C)it is filled above core level
D)none of these answers

44. A non-dimensional number generally associated with natural convection heat transfer is

A)Nusselt number
B)Grashoff number
C)Prandtl number
D)Pecekt number

45. The process of heat transfer during the re-entry of satellites and missiles, at very high speeds, into earths atmosphere is known as

D)viscous dissipation

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