The walls of a closed cubical box of edge 50cm are mdade of a material of thickness 1mm and thermal conductivity `4xx10^(-4)` cal `s^(-1)cm^(-1).^(@)C^(-1)` the interior of the box maintained at `100^(@)C` above the outside temperature by a heater placed inside the box and connected acros a 400 V d.c. source. Calculate the resistance of the heater.

The walls of a closed cubical box of edge 40 cm are made of a material of thickness 1 mm and thermal conductivity 4 xx 10^(-4) cals^(-1@) C^(-1) . The interior of the box is maintained at 100 ^(@) C above the outside temperature by a heater placed inside the box and connected across 400 V dc . Calculate the resistance of the heater.

The walls of a closed cubical box of edge 50cm are made of a material of thickness 1mm and thermal conductivity 4xx10^(-4) cm^(-1)(.^@C)^(-1) . The interior of the box is maintained 100^(@)C above the outside temperature by a heater placed inside the box and connected across 420V d.c. calculate the resistance of copper.

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.

Steam at 100^(@)C is passed through a tubeof radius 5 cm and length 3 m. If the thickness of tube be 2 mm and conductivity of its material be 2xx10^(-4)" cal "cm^(-1) K^(-1) s^(-1) , calculate the rate of loss of heat in js^(-1) . The outside temperature is 20^(@)C .

Steam at 373K is passed through a tube of radius 50 cm and length 3m. If thickness of the tube be 2 mm and conductivity of its material be 2xx10^(-4) / cal/s-cm-K, the rate of loss of heat in Js^(-1) is (The outside temperature is 282K).

If the coefficient of conductivity of aluminium is 0.5 cal cm^(-1) s^(-1).^(@)C^(-1) , then the other to conductor 10 cal s^(-1) cm^(-2) in the steady state, the temperature gradient in aluminium must be

Water is filled in a closed cylindrical vessel of 10 cm height and base radius sqrt(10//pi) cm. The open ends ofthe cylinder are closed by two metal discs made ofa material whose thickness is 10^(-3)m and having thermal conductivity 200W//m^(@)C. If water temperature inside the cylinder is 50^(@)C and surrounding temperature is 20^(@)C, findthe time taken for the temperature to fall by 1^(@)C, Given that the specific heat ofwater is 4200J//kg^(@)C. and heat loss from water only takes place by the discs as the walls are made up of a thermally insulating material.

Steam at 373 K is passed through a tube of radius 10 cm and length 10 cm and length 2m . The thickness of the tube is 5mm and thermal conductivity of the material is 390 W m^(-1) K^(-1) , calculate the heat lost per second. The outside temperature is 0^(@)C .

A cube of side 10cm is filled with ice of density 0.9//c.c Thickness of the walls of the cube is 1mm and thermal conductivity of the material of the cube is steam bath maintained at a placed in steam bath maintained at a temperature of 100^(@)C the time in which ice completely melts is (L_(ice)=80cal//gm) .

A closed cubical box is made of parfectly insulating material and the only way for heat to enter or leave the box is throgh two solid cylindrical metal plugs, each of cross sectional area 12cm^(2) and length 8cm fixed in the opposite walls of the box. The outer surface of one plug is kept at a temperature of 100^(@)C . while the outer surface of the plug is maintained at a temperature of 4(@)C . The thermal conductivityb of the material of rthe plug is 2.0Wm^(-1) ^(@)C^(-1) . A source of energy generating 13W is enclosed inside the box. Find the equilibrium temperature of the inner surface of the box assuming that it is the same at all points on the inner surface.