Heating And Welding(Engineering > Electrical Engineering ) Questions and Answers

Question 1. Radiations from a black body are proportional to
  1.    T
  2.    T2
  3.    T3
  4.    T4
Explanation:-
Answer: Option D. -> T4
Question 2. 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)
Explanation:-
Answer: Option C. -> Both (A) and (B)
Question 3. The material of the heating element for a furnace should have
  1.    Lower melting point
  2.    Higher temperature coefficient
  3.    High specific resistance
  4.    All of the above
Explanation:-
Answer: Option C. -> High specific resistance
Question 4. In induction heating __________ is abnormally high.
  1.    Phase angle
  2.    Frequency
  3.    Current
  4.    Voltage
Explanation:-
Answer: Option B. -> Frequency
Question 5. For the transmission of heat from one body to another
  1.    Temperature of the two bodies must be different
  2.    Both bodies must be solids
  3.    Both bodies must be in contact
  4.    At least one of the bodies must have some source of heating
Explanation:-
Answer: Option A. -> Temperature of the two bodies must be different
Question 6. When a body reflects entire radiation incident on it, then it is known as
  1.    White body
  2.    Grey body
  3.    Black body
  4.    Transparent body
Explanation:-
Answer: Option A. -> White body
Question 7. Heat transfer by condition will not occur when
  1.    Bodies are kept in vacuum
  2.    Bodies are immersed in water
  3.    Bodies are exposed to thermal radiations
  4.    Temperatures of the two bodies are identical
Explanation:-
Answer: Option D. -> Temperatures of the two bodies are identical
Question 8. A perfect black body is one that
  1.    Transmits all incident radiations
  2.    Absorbs all incident radiations
  3.    Reflects all incident radiations
  4.    Absorbs, reflects and transmits all incident radiations
Explanation:-
Answer: Option B. -> Absorbs all incident radiations
Question 9. For heating element high resistivity material is chosen to
  1.    Reduce the length of heating element
  2.    Increase the life of the heating element
  3.    Reduce the effect of oxidation
  4.    Produce large amount of heat
Explanation:-
Answer: Option A. -> Reduce the length of heating element
Question 10. Which of the following heating methods has maximum power factor?
  1.    Arc heating
  2.    Dielectric heating
  3.    Induction heating
  4.    Resistance heating
Explanation:-
Answer: Option D. -> Resistance heating
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