30) Which of the following is expected to have highest thermal conductivity

Answer is:

solid ice

Heat transfer MCQ with Answers

31) Thermal conductivity of glass-wool varies from sample to sample because of variation in

Answer is:

all of the above.

Explanation:

Thermal conductivity of glass-wool varies from sample to sample because of variation in
* composition
* density
* porosity

32) Thermal conductivity of a material may be defined as the

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

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

heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces

all of the above

Answer is:

all of the above

Explanation:

Thermal conductivity of a material may be defined as the
* quantity of heat flowing in one second through a slab of the material of area 1 cm² and thickness 1 cm when its faces differ in temperature by 1 Degree Centigrade
* quantity of heat flowing in one second through one cm of material when opposite faces are maintained at a temperature difference of 1 Degree Centigrade
* heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces