In a certain planetary system, it is observed that one of the celestial bodies having a surface temperature of $200 \;K$, emits radiation of maximum intensity near the wavelength $12\; \mu m$. The surface temperature (in $K$) of a nearby star which emits light of maximum intensity at a wavelength $\lambda= 4800\;\mathring A$ is
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One end of a metal rod of length $1.0 m$ and area of cross section $100c{m^2}$ is maintained at ${100^o}C.$If the other end of the rod is maintained at ${0^o}C$, the quantity of heat transmitted through the rod per minute is (Coefficient of thermal conductivity of material of rod =$100W/m-K$)
The rate of loss of heat from a body cooling under conditions of forced convection is proportional to its $(A)$ heat capacity $(B)$ surface area $(C)$ absolute temperature $(D)$ excess of temperature over that of surrounding : state if
Two spheres of same material have radius $1m$ and $4 m$ and temperature $4000K$ and $2000K$ respectively. The energy radiated per second by the first sphere is
Three stars $A, B, C$ have surface temperatures $T _{A} ,T _{B}, T _{C}$ respectively. Star $A$ appears bluish, star $B$ appears reddish and star $C$ yellowish. Hence,
The graph. Shown in the adjacent diagram, represents the variation of temperature $(T)$ of two bodies, $x$ and $y$ having same surface area, with time $(t)$ due to the emission of radiation. Find the correct relation between the emissivity
Five rods of same dimensions are arranged as shown in the figure. They have thermal conductivities $K1, K2, K3, K4$ and $K5$ . When points $A$ and $B$ are maintained at different temperatures, no heat flows through the central rod if
A metallic prong consists of $4$ rods made of the same material, cross-sections and same lengths as shown below. The three forked ends are kept at $100^{\circ} C$ and the handle end is at $0^{\circ} C$. The temperature of the junction is ............. $^{\circ} C$
A black body radiates energy at the rate of $1 \times 10^5 J / s \times m^2$ at temperature of $227^o C$. The temperature to which it must be heated so that it radiates energy at rate of $1 \times 10^9J/s m^2$, is
The black body spectrum of an object $O _1$ is such that its radiant intensity (i.e. intensity per unit wavelength interval) is maximum at a wavelength of $200\,nm$. Another object $O _2$ has the maximum radiant intensity at $600\,nm$. The ratio of power emitted per unit area by source $O _1$ to that of source $O _2$ is