Heat and Mass Transfer According to Stefan Boltzmann law, ideal radiators emit radiant energy at a rate proportional to Fourth power of temperature Square of temperature Absolute temperature Fourth power of absolute temperature Fourth power of temperature Square of temperature Absolute temperature Fourth power of absolute temperature ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The amount of radiation mainly depends upon the Nature of the body All of these Type of surface of the body Temperature of the body Nature of the body All of these Type of surface of the body Temperature of the body ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Two balls of same material and finish have their diameters in the ratio of 2: 1 and both are heated to same temperature and allowed to cool by radiation. Rate of cooling by big ball as compared to smaller one will be in the ratio of 0.084027777777778 0.043055555555556 0.042361111111111 0.16736111111111 0.084027777777778 0.043055555555556 0.042361111111111 0.16736111111111 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The logarithmic mean temperature difference (tm) is given by (where Δt1 and Δt2 are temperature differences between the hot and cold fluids at entrance and exit) tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) tm = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) tm = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body. This statement is known as Stefan's law Kirchhoff's law Wien's law Planck's law Stefan's law Kirchhoff's law Wien's law Planck's law ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer All radiations in a black body are Reflected Absorbed Refracted Transmitted Reflected Absorbed Refracted Transmitted ANSWER DOWNLOAD EXAMIANS APP
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