Heating & Welding Mcqs

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

1. To avoid initial rush of current
2. To avoid change in kW rating with temperature
3. Both (A) and (B)
4. Either (A) or (B)

MCQ: It is desirable to operate the arc furnaces at power factor of_____________?

1. zero
2. 0.707 lagging
3. unity
4. 0.707 leading

MCQ: Ajax Wyatt furnace is started when____________?

1. it is filled below core level
2. it is filled above core level
3. it is fully empty
4. none of the above

MCQ: Radiations from a black body are proportional to____________?

1. T1
2. T2
3. T3
4. T*

MCQ: Which of the following methods is used to control temperature in resistance furnaces ?

1. Variation of resistance
2. Variation of voltage
3. Periodical switching on and off of the supply
4. All of the above methods

MCQ: In arc furnace the function of choke is______________?

1. to stabilize the arc
2. to imprpve, power factor
3. to reduce severity of the surge
4. none of the above

MCQ: Hysteresis loss and eddy current loss are used in____________?

1. induction heating of steel
2. dielectric heating
3. induction heating of brass
4. resistance heating

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

1. bad, good
2. bad, bad
3. good, bad
4. good, good

MCQ: In heating the ferromagnetic material by induction heating, heat is produced due to_____________?

1. induced current flow through the charge
2. hysteresis loss taking place below curie temperature
3. due to hysteresis loss as well as eddy current loss takingplace in the charge
4. none of the above factors

MCQ: Resistance variation method of temperature control is done by connecting resistance elements in_____________?

1. series
2. parallel
3. series-parallel connections
4. star-delta connections
5. all of the above ways