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.Management Sciences
Category: Heating and Welding
When a body reflects entire radiation incident on it, then it is known as____________?
A. white body
B. grey body
C. black body
D. transparent body
In induction heating ___________ is abnormally high?
A. phase angle
B. frequency
C. current
D. voltage
For heating element high resistivity material is chosen to______________?
A. reduce the length of heating element
B. increase the life of the heating element
C. reduce the effect of oxidation
D. produce large amount of heat
Which of the following is an advantage of eddy current heating ?
A. The amount of heat generated can be controlled accurately
B. Heat at very high rate can be gene-rated
C. The area of the surface over which heat is produced can be accurately controlled
D. All of the above
It is desirable to operate the arc furnaces at power factor of_____________?
A. zero
B. 0.707 lagging
C. unity
D. 0.707 leading
Which of the following is an advantage of heating by electricity ?
A. Quicker operation
B. Higher efficiency
C. Absence of flue gases
D. All of the above
The temperature inside a furnace is usually measured by which of the following ?
A. Optical pyrometer
B. Mercury thermometer
C. Alcohol thermometer
D. Any of the above
Heat transfer by condition will not occur when____________?
A. bodies are kept in vacuum
B. bodies are immersed in water
C. bodies are exposed to thermal radiations
D. temperatures of the two bodies are identical
For the transmission of heat from one body to another__________?
A. temperature of the two bodies must be different
B. both bodies must be solids
C. both bodies must be in contact
D. at least one of the bodies must have some source of heating
Radiant heating is used for which of the following ?
A. Annealing of metals
B. Melting of ferrous metals
C. Heating of liquids in electric kettle
D. Drying of paints and varnishes
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