Related InterviewSolutions

• A cube `a=3.0cm` on each side radiates energy at the rate of `P=20J//s` when its temperature is `727^(@)C` and surrounding temperature `27^(@)C`. Determine its emissivity.
• Heat is conducted through a slab composed of paralel layers of two different materials of conductivities `134.4` SI units and 58.8 SI units and of thickness `3.6cm` and `4.2cm` respectively. The temperature of the outer faces of the compound slab are `96^(@)C` and `8^(@)C`. Find (i) the temperature of the interface, (ii) temperature gradient in each section of the slab.
• One end of a copper rod of length `0.25m` and area of cross-section `10^(-4) m^(2)` is immersed in a liquid boiling at `125^(@)C` whereas the other end is kept cold by dipping It in an ice-cold bath. Find (i) temperature gradient, (ii) the rate of heat transfer (iii) the temperature at a point `0.1m` from the higher temperature end. (`lamda` of copper `=92cals^(-1)m^(-1)K^(-1)`)
• A hollow cube of metal has sides measuring `0.8cm` (internal) and thickenes `0.5cm`. It is filled with ice `0^(@)C` and immersed in boiling water at `100^(@)C`. How many kg of ice will melt in one minute? Thermal conductivity of metal `=252Jm^(-1)s^(-1)K^(-1)` and latent heat capacity of ic e`=336xx10^(3)Jkg^(-1)`.
• A slab consists of two parallel layers of different materials `4cm` and `2cm` thick and of thermal conductivities `54cals^(-1)m^(-1)K^(-1)` and `36cals^(-1)m^(-1)K^(-1)` respectively. If the faces of the slab are at `100^(@)C` and `0^(@)C` calculate the temperature of the surface dividing the two materials.
• Calculate the thermal resistance of an aluminium rod of length `20cm` and area of cross-section `4cm^(2)`. The thermal conductivity of aluminium is `210Js^(-1)m^(-1)K^(-1)`.
• Thermal power of density `W` is generated uniformly inside a sphere of radius `R` and thermal conductivity `lamda`. Find the temperature distribution along the radius of the sphere in the steady state of it when its outer surface is at temperature `T_(0)`.
• A rod of length `l` with thermally insulated lateral surface is made of a material whose thermal conductivity varies as `K=sc//T` where `c` is a constant. The ends are kept at temperatures `T_(1)` and `T_(2)`. Find the temperature at a distance `x` from te first end where the temperature is `T_(1)` and the heat flow density.