50 Important Electrical Heating MCQ Question and Answer | PDF Free Download
1.The temperature inside a resistance furnace can be varied by
- ADisconnecting some of the heating elements
- BVarying the operating voltages
- CVarying the current through heating elements
- DBy any of the above method
2.In induction heating _____________ is abnormally high
- APhase angle
- BFrequency
- CCurrent
- DVoltage
3.High frequency power supply for induction furnaces can be obtained by
- ACoreless transformers
- BCurrent transformers
- CMotor-generator set
- DMulti-phase transformer
4.Induction furnaces are employed for which of the following?
- AHeat treatment of castings
- BHeating of insulators
- CMelting aluminium
- DNone of the above
5.In an electric room heat convector, the method of heating used is
- AArc heating
- BResistance heating
- CInduction heating
- DDielectric heating
6.In a domestic cake baking oven the temperature is controlled by
- AVoltage variation
- BThermostat
- CAuto-transformer
- DSeries-parallel operation
7.In an electric press, mica is used
- AAs an insulator
- BAs a device for power factor improvement
- CFor dielectric heating
- DFor induction heating
8.Induction heating takes place in which of the following?
- AInsulating materials
- BConducting materials which are magnetic
- CConducting materials which are non-magnetic
- DConducting materials which may or may not be magnetic
9.For heating element high resistivity material is chosen to
- AReduce the length of heating element
- BIncrease the life of the heating element
- CReduce the effect of oxidation
- DProduce large amount of heat
10.In resistance heating highest working temperature is obtained from heating elements made of ____________
- ANickel copper
- BNichrome
- CSilicon carbide
- DSilver
11.In the indirect resistance heating method, maximum heat-transfer takes place by
- ARadiation
- BConvection
- CConduction
- DAny of the above
12.Low temperature co-efficient of heating element is desired due to which of the following reasons?
- ATo avoid initial rush of current
- BTo avoid change in kW rating with temperature
- CBoth (a) and (b)
- DEither (a) or (b)
13.Which of the following methods is used to control temperature in resistance furnaces?
- AVariation of resistance
- BVariation of voltage
- CPeriodical switching on and off of the supply
- DAll of the above methods
14.It is desirable to operate the arc furnaces at power factor of
- AZero
- B0.707 lagging
- CUnity
- D0.707 leading
15.In arc furnace the function of choke is
- ATo stabilize the arc
- BTo improve power factor
- CTo reduce severity of the surge
- DNone of the above
16.Ajax Wyatt furnace is started when
- AIt is filled below core level
- BIt is filled above core level
- CIt is fully empty
- DNone of the above
17.In electric press, mica is used because it is
- ABad conductor of heat and good conductor of electricity.
- BBad conductor of heat and Bad conductor of electricity.
- CGood conductor of heat and Bad conductor of electricity.
- DGood conductor of heat and Good conductor of electricity.
18.Hysteresis loss and eddy current loss are used in
- AInduction heating of steel
- BDielectric heating
- CInduction heating of brass
- DResistance heating
19.In heating the ferromagnetic material by induction heating, heat is produced due to
- AInduced current flow through the charge
- BHysteresis loss taking place below curie temperature
- CDue to Hysteresis loss as well as eddy current loss taking place in the charge
- DNone of the above factors
20.Radiant heating is used for which of the following?
- AAnnealing of metals
- BMelting of ferrous metals
- CHeating of liquids in electric kettle
- DDrying of paints and varnishes