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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