With increase in temperature, the electrical conductivity of a _________________ decreases ?

Related Mcqs:

1. The ratio of thermal & electrical conductivity is same for all the metals at the same temperature; and at around room temperature, this ratio is proportional to(where, T = absolute temperature, °K) ?

   A. T
   B. 1/T
   C. T2
   D. 1/T2

2. High relative humidity decreases the evaporative process and as the temperature is increased, the relative humidity decreases. The comfort range for human body is the ambient temperature of 22 to 27°C with relative humidity ranging from _______________ percent ?

   A. 5 to 10
   B. 15 to 25
   C. 45 to 50
   D. 75 to 80

3. A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness ______________ metre?

   A. 0.01
   B. 0.1
   C. 0.25
   D. 0.5

4. Which of the following materials has the poorest electrical conductivity ?

   A. Carbon
   B. Aluminium
   C. Silver
   D. Stainless steel

5. With increase in annealing temperature, the following defect density decreases?

   A. Vacancy
   B. Dislocation
   C. Grain boundary
   D. All of these

6. __________________ of air does not increase with increase in temperature?

   A. Density
   B. Thermal diffusivity
   C. Viscosity
   D. Thermal conductivity

7. With increase in steam pressure, its specific volume decreases ____________________?

   A. Rapidly first and then slowly
   B. Linearly
   C. Slowly first and then rapidly
   D. Exponentially

8. One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m-1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is____________________?

   A. 100
   B. 900
   C. 9000
   D. 10000

9. When dry bulb temperature & wet bulb temperature of moist air is the same, it means that the _________________?

   A. Partial pressure of water vapour is less than the total pressure
   B. Humidity is < 100% & dew point temperature of air has not reached
   C. Dew point temperature of air has not reached & air is not saturated fully
   D. Air is fully saturated

10. The boiling & freezing points on a newly defined temperature scale in degree ‘D’ are 400°D & 100°D respectively. The temperature reading corresponding to 60°C on this new temperature scale will be equal to _____________ °D ?

    A. 140
    B. 180
    C. 240
    D. 280