General Principles in the Working of Thermos Flask, Gramophone NDA Questions

NDA Physics

General Principles in the Working of Thermos Flask, Gramophone MCQ Questions


13.
In a thermos flask, which type of heat transfer is prevented by the reflective coating?
A.
Convection
B.
Conduction and radiation
C.
Radiation
D.
Evaporation
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ANSWER :
C. Radiation
14.
The original name of the thermos flask was
A.
Heat Preserver
B.
Dewar Flask
C.
Temperature Bottle
D.
Insulated Container
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ANSWER :
B. Dewar Flask
15.
Which material is often used for the stopper or cap of a thermos flask to ensure a tight seal?
A.
Metal
B.
Rubber or Plastic
C.
Glass
D.
Wood
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ANSWER :
B. Rubber or Plastic
16.
The effectiveness of a thermos flask in retaining heat is least influenced by
A.
The material of the inner bottle
B.
The design of the outer case
C.
The thickness of the walls
D.
The quality of the vacuum
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ANSWER :
C. The thickness of the walls
17.
A thermos flask can keep liquids hot or cold because it
A.
Heats or cools the liquid actively
B.
Reduces heat loss or gain
C.
Generates thermal energy
D.
Absorbs external heat
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ANSWER :
B. Reduces heat loss or gain
18.
Which of the following is not a common use for a thermos flask?
A.
Keeping coffee hot
B.
Storing ice cream
C.
Maintaining soup temperature
D.
Transporting liquid nitrogen
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ANSWER :
B. Storing ice cream