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MCQs 1: Unit of thermal conductivity in S.I. units is__________________?

J/m2 sec J/m °K sec W/m °K A. and C. above B. and C. above
Answer Explanation

MCQs 2: Heat transfer in liquid and gases takes place by_____________________?

conduction convection radiation conduction and convection convection and radiation
Answer Explanation

MCQs 3: Heat flowing from one side to other depends directly on ___________________?
Pick up the wrong case?

face area time thickness temperature difference thermal conductivity
Answer Explanation

MCQs 4: Which of the following is the case of heat transfer by radiation ___________________?

blast furnace heating of building cooling of parts in furnace heat received by a person from fireplace all of the above
Answer Explanation

MCQs 5: Which of the following is a case of steady state heat transfer ___________________?

I.C. engine air preheaters heating of building in winter all of the above none of the above
Answer Explanation

MCQs 6: Thermal conductivity of water in general with rise in temperature ____________________?

increases decreases remains constant may increase or decrease depending on temperature none of the above
Answer Explanation

MCQs 7: Temperature of steam at around 540°C can be measured by ____________________?

thermometer radiatiouv pyrometer thermistor thermocouple thermopile
Answer Explanation

MCQs 8: Metals are good conductors of heat because________________?

their atoms collide frequently their atoms-are relatively far apart they contain free electrons they have high density all of the above
Answer Explanation

MCQs 9: Cork is a good insulator because it has___________________?

free electrons atoms colliding frequency low density porous body all of the above
Answer Explanation

MCQs 10: Thermal conductivity of air at room temperature in kcal/m hr °C is of the order of__________________?

0.002 0.02 0.01 0.1 0.5
Answer Explanation

MCQs 11: Thermal conductivity of air with rise in temperature__________________?

increases decreases remains constant may increase or decrease depending on temperature none of the above
Answer Explanation

MCQs 12: Total heat is the heat required to__________________?

change vapour into liquid change liquid into vapour increase the temperature of a liquid or vapour convert water into steam and superheat it convert saturated steam into dry steam
Answer Explanation

MCQs 13: Thermal conductivity of water at 20°C is of the order of_____________________?

0.1 0.23 0.42 0.51 0.64
Answer Explanation

MCQs 14: The time constant of a thermocouple is_______________?

the time taken to attain the final temperature to be measured the time taken to attain 50% of the value of initial temperature difference the time taken to attain 63.2% of the value of initial temperature difference determined by the time taken to reach 100°C from 0°C none of the above
Answer Explanation

MCQs 15: In heat transfer, conductance equals conductivity (kcal/hr/sqm/°C/cm) divided by ________________?

hr (time) sqm (area) °C (temperature) cm (thickness) kcal (heat).
Answer Explanation

MCQs 16: Which of the following is expected to have highest thermal conductivity_______________?

steam solid ice melting ice water boiling water
Answer Explanation

MCQs 17: 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? 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 none of the above
Answer Explanation

MCQs 18: Heat is transferred by all three modes of transfer, viz, conduction, convection and radiation in _________________?

electric heater steam condenser melting of ice refrigerator condenser coils boiler
Answer Explanation

MCQs 19: The ratio of heat flow Q1/Q2 from two walls of same thickness having their thermal conductivities as ATj – 2K2 will be ________________?

I 0.5 2 0.25 4.0
Answer Explanation

MCQs 20: Thermal diffusivity of a substance is ____________________?

proportional of thermal conductivity inversely proportional to k proportional to (k) inversely proportional to k2 none of the above
Answer Explanation

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