MCQs on Electric Heating, Welding ,Arc Furnace

MCQs on Electric Heating, Welding Arc Furnace

1..A welding transformer is used to convert:

(a) DC main supply in to AC welding supply

(b) AC main supply in to DC welding supply

(c) AC main supply in to AC welding supply

(d) DC main supply in to DC welding supply

Read: Study Notes on Arc Furnace

2..Which type of transformer is used in arc welding:

(a) Toroidal

(b) Step up

(c) Step Down

(d) Auto transformer

3..In which type of welding is heavy current (50000 A) passed through the joint and welding

is done under external pressure. :

(a) Arc welding

(b) Spot welding

(c) Gas welding

(d) Forge welding

4..Welding spatter is a/an:

(a) Welding defect

(b) Flux

(c) Electrode coating

(d) welding technique

5..In a gas welding maximum, ame temperature occurs at:

(a) Inner cone

(b) outer cone

(c) Next of inner cone

(d) Tip of the flame

6..In which type of welding a pool of molten metal is used:

(a) Electroslag

(b) Submerged

(c) TIG

(d) MIG

7..Gas metal arc welding refers to:

(a) Electro beam welding

(b) TIG welding

(c) Plasma arc welding

(d) MIG welding

8..In MIG welding, helium or argon is used to:

(a) Providing cooling e_ect

(b) Act as ux

(c) Act as shielding medium

(d) Felicitate welding process

9..Which of the following is not a conventional type of welding:

(a) Arc welding

(b) Resistance welding

(c) Gas welding

(d) Friction welding

10..The main criterion for diameter of electrode in arc welding :

(a) Material to be welded

(b) Type of welding Process

(c) Thickness of material

(d) Voltage used

11..The principle of microwave oven is:

(a) Induction heating

(b) Resistance heating

(c) Dielectric heating

(d) Molecular vibration

12..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

13..In direct arc furnace which of the following has highest value:

(a) Current

(b) Voltage

(c) Power Factor

(d) All of the above

14..Direct arc furnaces have which of the following power factors:

(a) Low, lagging

(b) Unity

(c) Low, leading

(d) Any of the above

15………. Is used for heating non-conducting materials:

(a) Eddy current heating

(b) Arc heating

(c) Induction heating

(d) Dielectric heating

16..In induction heating ……..is abnormally high:

(a) Phase angle

(b) Frequency

(c) Current

(d) Voltage

17..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 e_ect of oxidation

(d) Producing large amount of heat

18..Induction heating takes place in 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

19..In resistance heating highest working temperature is obtained from heating elements

made of:

(a) Nickel copper

(b) Nichrome

(c) Silicon carbide

(d) Silver

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

(a) Radiation

(b) Convection

(c) Conduction

(d) Any of the above

21..It is desirable to operates the arc furnaces at power factor of:

(a) Zero

(b) 0.707 lagging

(c) Unity

(d) 0.707 leading

22..Induction heating process is based on which of the following principles:

(a) Thermal ion release principal

(b) Nucleate heating principal

(c) Resistance heating principal

(d) Electromagnetic induction principle

23..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

24..TIG welding is best suited for welding:

(a) Mild welding

(b) Stainless steel

(c) Carbon steel

(d) Aluminium

25..Arc-welding uses following electric supply :

(a) A.C

(b) D.C

(c) Both AC and DC

(d) Spiral waveform

26..The most commonly used ame in gas welding is:

(a) Neutral

(b) Oxidising

(c) Carburising

(d) All of the above

27..In MIG welding, the metal is transferred in the form of:

(a) A _ne spray of metal

(b) Molten drops

(c) Weld pool

(d) Molecules

28..carburizing ame is used to weld metals like:

(a) Steel

(b) Copper and brass

(c) Aluminium, Nickel,monel etc

(d) Carburized steel

29..In mig welding at high current the metal is transferred into the form of which of the

following ?:

(a) A _ne spray of metal

(b) Molten drops

(c) Weld pool

(d) Molecules

30..In MIG welding, helium or argon is used in order to:

(a) Provide cooling e_ect

(b) Act as ux

(c) Act as shielding medium

(d) Facilitate welding process

31..The most commonly used ame in gas welding is A. Neutral B. Oxidising C. Carburising

:

(a) Only A

(b) Only B

(c) Only C

(d) Only A and B

32..The main criterion for diameter of electrode in arc welding is:- :

(a) materials to be welded

(b) type of welding process

(c) thickness of material

(d) voltage used

33..In D.C. welding, the straight polarity (electrode negative) results in:voltage used:

(a) Lower penetration

(b) Lower deposition rate

(c) Less heating of work piece

(d) Smaller weld pool

34..Stud and projection welding belong to the following category of welding:

(a) Gas welding

(b) Arc welding

(c) Resistance welding

(d) Pressure welding

35..Seam welding is best adopted for metal thickness ranging from:

(a) 0.025 to 3 mm

(b) 3 to 5 mm

(c) 5 to 8 mm

(d) 8 to 10 mm

36..In electrical resistance welding material of electrode should have:

(a) higher electrical conductivities.

(b) higher thermal conductivities.

(c) su_cient strength to sustain high pressure

at elevated temperatures.

(d) all of above.

37..The metal surfaces for electrical resistance welding must be:

(a) rough.

(b) clean.

(c) moistened

(d) coloured

38..Radiation from a body is proportional to:

(a) T2.

(b) T4

(c) T5.

(d) T3

39..Induction heating takes place in:

(a) conducting but non-magnetic materials.

(b) conducting materials which may be either

magnetic or non-magentic materials.

(c) insulating materials.

(d) conducting and magnetic materials.

40..The main advantage of dielectric heating is that:

(a) heating occurs in the material itself.

(b) heating occurs due to high frequency.

(c) it can be used for drying the explosives.

(d) None of the above.

41..The supply frequency usually employed for high frequency eddy current heating is:

(a) 1 KHz

(b) 5 KHz.

(c) 10 MHz.

(d) 10 KHz to 400 KHz

42..The most modern method for food processing is:

(a) Eddy current heating.

(b) Dielectric current

(c) Induction heating.

(d) Resistance heating.

43..In induction heating:

(a) magnetic materials can be easily treated in

comparison to non-magnetic materials.

(b) heat is produced due to current induced in

the charge by electromagnetic action

(c) the resistance of charge must be low and

voltage applied must be high in order to

produce su_cient heat.

(d) all of above.

44..In an electric room heat converter the method of heating used is:

(a) Infrared heating.

(b) Induction heating.

(c) Resistance heating.

(d) arc heating.

45..In induction heating, the depth up to which current will penetrate is proportional to:

(a) Frequency.

(b) (Frequency)2.

(c) 1/(Frequency).

(d) 1/Frequency.

46……….is not an application of dielectric heat.:

(a) Diathermy.

(b) Soldering.

(c) Food processing.

(d) Gluing of wood.

47..For intermittent work which of the following furnace is suitable?:

(a) Core less furnace.

(b) Indirect arc furnace.

(c) Either of above

(d) Neither of above.

48..The dielectric loss in a dielectric is proportional to:

(a) Voltage impressed on the dielectric.

(b) The square of the voltage impressed on the

dielectric.

(c) Square root of the voltage impressed on the

dielectric.

(d) None of above.

49..The power factor will be leading in case of:

(a) Induction heating.

(b) Resistance heating.

(c) Dielectric heating.

(d) Electric arc heating.

50..For dielectric heating the range of frequency normally employed is:

(a) 10 KHz to 100 KHz.

(b) 100 KHz to 10 MHz.

(c) 1 MHz to 10 MHz.

(d) 10 MHz to 40 MHz.

51..The metod of heating used for non conducting materials is:

(a) radiant heating.

(b) dielectric heating.

(c) resistance heating.

(d) induction heating.

Answers

Q01) c Q02) c Q03) b Q04) a Q05) a

Q06) a Q07) d Q08) c Q09) d Q10) c

Q11) d Q12) d Q13) a Q14) a Q15) d

Q16) b Q17) a Q18) d Q19) c Q20) a

Q21) b Q22) d Q23) a Q24) d Q25) c

Q26) a Q27) a Q28) c Q29) a Q30) c

Q31) a Q32) c Q33) b Q34) c Q35) a

Q36) d Q37) b Q38) b Q39) b Q40) a

Q41) d Q42) b Q43) d Q44) c Q45) c

Q46) b Q47) b Q48) b Q49) c Q50) d

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