A. Insulating materials
B. Conducting materials which are magnetic
C. Conducting materials which are non-magnetic
D. Conducting materials which may or may not be magnetic
A. By disconnecting some of the heating elements
B. By varying the operating voltage
C. By varying the current through heating elements
D. By any of the above method
A. phase angle
B. frequency
C. current
D. voltage
A. oxidizing
B. deoxidising
C. reducing
D. neutral
A. Water
B. Steam
C. Sold ice
D. Melting ice
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
A. inside boiler furnaces
B. during melting of ice
C. through the surface of the insulted pipe carrying steam
D. from refrigerator coils to freezer of a refrigerator
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
A. transmits all incident radiations
B. absorbs all incident radiations
C. reflects all incident radiations
D. absorbs, reflects and transmits all incident radiations
A. white body
B. grey body
C. black body
D. transparent body