Heating and Welding Mcqs

This set of Electrical engineering Multiple Choice Questions & Answers (MCQs) focuses on study of “Heating and Welding”. These questions are chosen from a collection of most authoritative and best reference books on Electrical engineering. Our aim is to prepare an individual for competitive exams like NTS, GAT, ECAT, University and College entrance exams, Jobs and interviews. One should practice our MCQS to assimilate Heating and Welding Mcqs comprehensively.

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1.
Properly of low temperature co-eflficient of heating element is desired due to which of the following reasons ?

To avoid initial rush of current

To avoid change in kW rating with temperature

Both (A) and (B)

Either (A) or (B)

2.
It is desirable to operate the arc furnaces at power factor of_____________?

Zero

0.707 lagging

Unity

0.707 leading

3.
Ajax Wyatt furnace is started when____________?

It is filled below core level

It is filled above core level

It is fully empty

None of the above

5.
Which of the following methods is used to control temperature in resistance furnaces ?

Variation of resistance

Variation of voltage

Periodical switching on and off of the supply

All of the above methods

6.
In arc furnace the function of choke is______________?

To stabilize the arc

To imprpve, power factor

To reduce severity of the surge

None of the above

7.
Hysteresis loss and eddy current loss are used in____________?

Induction heating of steel

Dielectric heating

Induction heating of brass

Resistance heating

8.
In electric press, mica is used because it is _________ conductor of heat but/and __________ conductor of electricity?

Bad, good

Bad, bad

Good, bad

Good, good

9.
In heating the ferromagnetic material by induction heating, heat is produced due to_____________?

Induced current flow through the charge

Hysteresis loss taking place below curie temperature

Due to hysteresis loss as well as eddy current loss takingplace in the charge

None of the above factors

10.
Resistance variation method of temperature control is done by connecting resistance elements in_____________?

Series

Parallel

Series-parallel connections

Star-delta connections

All of the above ways

11.
Which of the following devices is necessarily required for automatic temperature control in a furnace ?

Thermostat

Thermocouple

Auto-transformer

Heating elements of variable resis-tance material

12.
Direct arc furnaces have which of the following power factors ?

Unity

Low, lagging

Low, leading

Any of the above

13.
Which of the following is an advantage of eddy current heating ?

The amount of heat generated can be controlled accurately

Heat at very high rate can be gene-rated

The area of the surface over which heat is produced can be accurately controlled

All of the above

14.
Radiant heating is used for which of the following ?

Annealing of metals

Melting of ferrous metals

Heating of liquids in electric kettle

Drying of paints and varnishes

15.
For radiant heating around 2250°C, the heating elements are made of____________?

Copper alloy

Carbon

Tungsten alloy

Stainless steel alloy

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