Question 31. The thermal conductivity and the electrical conductivity of a metal at absolute temperature are related as

Question 32. The diffusion equations
Ɏ²t + q g = (1/α) (d t/d r)
Governs the temperature distribution under unsteady heat flow through a homogenous and isotropic material. The Fourier equation follows from this expression when

Question 33. The unit of thermal diffusivity is

Question 34. To effect a bond between two metal plates, 2.5 cm and 15 cm thick, heat is uniformly applied through the thinner plate by a radiant heat source. The bonding must be held at 320 K for a short time. When the heat source is adjusted to have a steady value of 43.5 k W/m², a thermocouple installed on the side of the thinner plate next to source indicates a temperature of 345 K. Calculate the temperature gradient for heat conduction through thinner plate. In the diagram, the upper plate is 2.5 cm thick while the lower is 15 cm thick.

Question 35. The relation Ϫ² t =0 is referred to as

Question 36. What is the thermal conductivity of apple in W/m K?

Question 37. What is the thermal conductivity of ice in W/m K?

Question 38. From the concept of kinetic theory, mean travel velocity of the gas molecules is prescribed by the relation
Where,
G = Universal gas constant
M = Molecular weight of the gas
T = Absolute temperature