The unit of Stefan Boltzmann constant is ____________________? - PakMcqs

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1. According to Stefan-Boltzmann law, ideal radiators emit radiant energy at a rate proportional to___________________?

   A. absolute temperature B. square of temperature C. fourth power of absolute temperature D. fourth power of temperature E. cube of absolute temperature...

2. Stefan Boltzmann law is applicable for heat transfer by __________________?

   A. conduction B. convection C. radiation D. conduction and radiation combined E. convection and radiation combined...

3. According to Stefan’s law, the total radiation from a black body per second per unit area is proportional to____________________?

   A. absolute temperature B. T2 C. T5 D. t E. l/T...

4. Heat conducted througfi unit area and unit thick face per unit time when temperature difference between opposite faces is unity,is called__________________?

   A. thermal resistance B. thermal coefficient C. temperature gradient D. thermal conductivity E. heat-transfer...

5. The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as ________________?

   A. emissivity B. transmissivity C. reflectivity D. intensity of radiation E. absorptivity...

6. The time constant of a thermocouple is_______________?

   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...

7. Thermal conductivity of water in general with rise in temperature ____________________?

   A. increases B. decreases C. remains constant D. may increase or decrease depending on temperature E. none of the above...

8. Temperature of steam at around 540°C can be measured by ____________________?

   A. thermometer B. radiatiouv pyrometer C. thermistor D. thermocouple E. thermopile...

9. Thermal diffusivity of a substance is ____________________?

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

10. Thermal diffusivity is ____________________?

    A. a dimensionless parameter B. function of temperature C. used as mathematical model D. a physical property of the material E. useful in case of heat transfer by radiation...