Heat Transfer

A. composition
B. density
C. porosity
D. structure
E. all of the above

A. it is impossible to transfer heat from low temperature source to t high temperature source
B. heat transfer by radiation requires no medium
C. all bodies above absolute zero emit radiation
D. heat transfer in most of the cases takes place by combination of conduction, convection and radiation
E. rate of heat transfer depends on thermal conductivity and temperature difference

A. proportional of thermal conductivity
B. inversely proportional to k
C. proportional to (k)
D. inversely proportional to k2
E. none of the above

A. I
B. 0.5
C. 2
D. 0.25
E. 4.0

A. electric heater
B. steam condenser
C. melting of ice
D. refrigerator condenser coils
E. boiler

A. quantity of heat flowing in one second through one cm cube of material when opposite faces ^re maintained at a temperature difference of 1°C
B. quantity of heat flowing in one second through a slab of the material of area one cm square, thickness 1 cm when its faces differ in temperature by 1°C
C. heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces
D. all of the above
E. none of the above

A. steam
B. solid ice
C. melting ice
D. water
E. boiling water

A. hr (time)
B. sqm (area)
C. °C (temperature)
D. cm (thickness)
E. kcal (heat).

A. the time taken to attain the final temperature to be measured
B. the time taken to attain 50% of the value of initial temperature difference
C. the time taken to attain 63.2% of the value of initial temperature difference
D. determined by the time taken to reach 100°C from 0°C
E. none of the above

A. 0.1
B. 0.23
C. 0.42
D. 0.51
E. 0.64