Hot oil is circulated thorugh an insulated container with a wooden lid at the top whose conductivity `K=0.149J//(m-^@C-sec)`, thickness `t=5mm, emissivity=0.6` Temperature of the top of the lid is maintaining at `T_l=127^@C`. If the ambient temperature `T_a=27^@C`.

Calculate:
(a) rate of heat loss per unit area due to radiation from the lid.
(b) temperature of the oil. `(Given sigma=17/3xx10^-8 Wm^-2K^-4)`

An insulated container has a wooden lid at the top whose conductivity is 0.15 J//m""^@Cs , thickness is 5 mm and emissivity is 0.5. The temperature of the top of the wooden lid is maintained at 125^@C and the ambient temperature is 27^@C . Hot liquid is now circulated through the container as shown in the figure. Determine the rate of loss of heat per unit area due to radiation from the wooden lid and temperature of the oil. Take sigma = 5.66 xx 10^(-8) Wm^(-2) K^(-4)

The radiant power of a furnace of surface area of 0.6m^(2) is 34.2KW The temperature of the furance s [sigma = 5.7 xx 10^(-8) Wm^(-2) K^(-4) .

A metallic ball of surface area 300 cm^2 at a temperature of 227^@C is placed in a container at 27^@C . Calculate the rate of loss of heat radiation by the ball if emissivity of ball is 0.3, sigma = 5.67 xx 10^(-5) erg cm^(-2) s^(-1) K^(-4) .

A sphere of radius 15 cm is at a temperature of 215^@C . Find the maximum amount of heat which may be lost per second by radiation when the sphere is placed in an enclosure at 25^@C . Take, sigma = 5.67 xx 10^(-8) Wm^(-2) K^4

A body at a temperature of 727^(@)C and having surface area 5 cm^(2) , radiations 300 J of energy each minute. The emissivity is(Given Boltzmann constant =5.67xx10^(-8) Wm^(-2)K^(-4)

A rod of length L with sides fully insulated is made of a material whose thermal conductivity K varies with temperature as K=(alpha)/(T) where alpha is constant. The ends of rod are at temperature T_(1) and T_(2)(T_(2)gtT_(1)) Find the rate of heat flow per unit area of rod .

Assume that the total surface area of a human body is 1-6m^(2) and that it radiates like an ideal radiator. Calculate the amount of energy radiates per second by the body if the body temperature is 37^(@)C . Stefan contant sigma is 6.0xx10^(-s)Wm^(-2)K^(-4) .

A black ened metal sphere of radius 7 cm is encllosed in as evacuated chamber maintained at a temperature of 27^(@)C . At what rate must energy be supplied to the sphere so as to keep its temperature constant at 127^(@)C ? sigma=5.7xx10^(-8) W m^(-2) K^(-4) .

Calculate the energy radiated in one minute by a blackbody of surface area 200 cm^2 at 127 ""^(@)C ( sigma= 5.7 xx 10^(-8) J m^(-2) s^(-1) K^(-4))