Q.1
Which of the following will happen if the thickness of refractory wall of furnace is increased?
  • Heat loss through furnace wall will increase
  • Temperature inside the furnace will fall
  • Temperature on the outer surface of furnace walls will drop
  • Energy consumption will increase
Q.2
In an electric room heat convector the method of heating used is Resistance heating
  • True
  • False
Q.3
It is desirable to operate the arc furnaces at power factor of
  • Zero
  • 0.707 lagging
  • Unity
  • 0.707 leading
Q.4
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
Q.5
By which of the following methods the temperature inside arcane can be varied?
  • By disconnecting some of the heating elements
  • By varying the operating voltage
  • By varying the current through heating elements
  • By any of the above method
Q.6
Which of the following insulating materials was suitable for low temperature applications?
  • Asbestos paper
  • Diatomaceous earth
  • 80 percent magnesia
  • Cork
Q.7
Direct arc furnaces have which of the following power factors?
  • Unity
  • Low, lagging
  • Low, leading
  • Any of the above
Q.8
Which of the following devices is necessarily required for automatic temperature control in a furnace?
  • Thermostat
  • Thermocouple
  • Autotransformer
  • Heating elements of variable resistance material
Q.9
________ is used for heating non-conducting materials.
  • Eddy current heating
  • Arc heating
  • Induction heating
  • Dielectric heating
Q.10
Induction heating process is based on which of the following principles?
  • Thermal ion release principle
  • Nucleate heating principle
  • Resistance heating principle
  • Electromagnetic induction principle
Q.11
In the indirect resistance heating method, maximum heat-transfer takes place by
  • Radiation
  • Convection
  • Conduction
  • Any of the above
Q.12
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
Q.13
In resistance heating highest working temperature is obtained from heating elements made of
  • Nickel copper
  • Nichrome
  • Silicon carbide
  • Silver
Q.14
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 generated
  • The area of the surface over which heat is produced can be accurately controlled
  • All of the above
Q.15
Properly of low temperature coefficient 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)
Q.16
For radiant heating around 2250°C, the heating elements are made of
  • Copper alloy
  • Carbon
  • Tungsten alloy
  • Stainless steel alloy
Q.17
Hysteresis loss and eddy current loss are used in
  • Induction heating of steel
  • Dielectric heating
  • Induction heating of brass
  • Resistance heating
Q.18
In arc furnace the function of choke is
  • To stabilize the arc
  • To improve power factor
  • To reduce severity of the surge
  • None of the above
Q.19
Induction heating takes place it which of the following?
  • Insulating materials
  • Conducting materials which are magnetic
  • Conducting materials which are non-magnetic
  • Conducting materials which may or may not be magnetic
Q.20
In an electric room heat convector the method of heating used is
  • Arc heating
  • Resistance heating
  • Induction heating
  • Dielectric heating
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