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Practice Test: Question Set - 04


1. Which of the following will happen if the thickness of refractory wall of furnace is increased?
    (A) Heat loss through furnace wall will increase
    (B) Temperature inside the furnace will fall
    (C) Temperature on the outer surface of furnace walls will drop
    (D) Energy consumption will increase

2. Which of the following has the highest value of thermal conductivity?
    (A) Water
    (B) Steam
    (C) Solid ice
    (D) Melting ice

3. Which of the following methods of heating is not dependent on the frequency of supply?
    (A) Induction heating
    (B) Dielectric heating
    (C) Electric resistance heating
    (D) All of the above

4. Radiations from a black body are proportional to
    (A) T
    (B) T2
    (C) T3
    (D) T4

5. A non-dimensional number generally associated with natural convection heat transfer is
    (A) Prandtl number
    (B) Grashoff number
    (C) Peclet number
    (D) Nusselt number

6. Induction furnaces are employed for which of the following?
    (A) Heat treatment of castings
    (B) Heating of insulators
    (C) Melting aluminium
    (D) None of the above

7. Properly of low temperature coefficient of heating element is desired due to which of the following reasons?
    (A) To avoid initial rush of current
    (B) To avoid change in kW rating with temperature
    (C) Both (A) and (B)
    (D) Either (A) or (B)

8. In direct arc furnace, which of the following has high value?
    (A) Current
    (B) Voltage
    (C) Power factor
    (D) All of the above

9. Which of the following devices is necessarily required for automatic temperature control in a furnace?
    (A) Thermostat
    (B) Thermocouple
    (C) Autotransformer
    (D) Heating elements of variable resistance material

10. The electrode of a direct arc furnace is made of
    (A) Tungsten
    (B) Graphite
    (C) Silver
    (D) Copper

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