The temperature of a piece of iron is ${27^o}C$ and it is radiating energy at the rate of $Q\;kW{m^{ - 2}}$. If its temperature is raised to ${151^o}C$, the rate of radiation of energy will become approximately ....... $Q\,kW\,{m^{ - 2}}$
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The radiant energy from the sun incident normally at the surface of earth is $20\, \frac{{k\;cal}}{{{m^2}\;min}}$. What would have been the radiant energy incident normally on the earth, if the sun had a temperature twice of the present one ....... $kcal/m ^2 \,min$
A particular star (assuming it as a black body) has a surface temperature of about $5 \times {10^4}K.$The wavelength in nanometers at which its radiation becomes maximum is $(b = 0.0029 mK)$
Consider a compound slab consisting of two different materials having equal thickness and thermal conductivities $ K$ and $2K$ respectively. The equivalent thermal conductivity of the slab is
The figure shows a system of two concentric spheres of radii $r_1$ and $r_2$ and kept at temperatures $T_1$ and $T_2$, respectively. The radial rate of flow of heat in a substance between the two concentric spheres is proportional to
Four identical rods of same material are joined end to end to form a square. If the temperature difference between the ends of a diagonal is ${100^o}C$, then the temperature difference between the ends of other diagonal will be ........ $^oC$
The temperature of the two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity $K$ and $2K$ and thickness $x$ and $4x$ , respectively are $T_2$ and $T_1$ ($T_2$ > $T_1$). The rate of heat transfer through the slab, in a steady state is $\left( {\frac{{A({T_2} - {T_1})K}}{x}} \right)f$, with $f $ which equal to
If the radius of a star is $R$ and it acts as a black body, what would be the temperature of the star, in which the rate of energy production is Q? ( $\sigma$ stands for Stefan's constant.)