A black body is at a temperature of $5760\ K$. The energy of radiation emitted by the body at wavelength $250\ nm$ is $U_1$, at wavelength $500\ nm$ is $U_2$ and that at $1000\ nm$ is $U_3$. Wien's constant, $b = 2.88 \times 10^6\ nm\ K$. Which of the following is correct?
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Wein's constant is $2892 \times {10^{ - 6}}$$MKS$ unit and the value of ${\lambda _m}$ from moon is $14.46$ microns. What is the surface temperature of moon ...... $K$
The end $A$ of a rod $AB$ of length $1\,m$ is maintained at $80\,^oC$ and the end $B$ at $0\,^oC.$ The temperature at a distance of $60\,\,c.m.$ from the end $A$ is......... $^oC$
One end of a thermally insulated rod is kept at a temperature $T_1$ and the other at $T_2$ . The rod is composed of two sections of length $l_1$ and $l_2$ and thermal conductivities $K_1$ and $K_2$ respectively. The temperature at the interface of the two section is
A composite metal bar of uniform section is made up of length $25 cm$ of copper, $10 cm$ of nickel and $15 cm$ of aluminium. Each part being in perfect thermal contact with the adjoining part. The copper end of the composite rod is maintained at ${100^o}C$ and the aluminium end at ${0^o}C$. The whole rod is covered with belt so that there is no heat loss occurs at the sides. If ${K_{{\rm{Cu}}}} = 2{K_{Al}}$ and ${K_{Al}} = 3{K_{{\rm{Ni}}}}$, then what will be the temperatures of $Cu - Ni$ and $Ni - Al$ junctions respectively
The maximum energy in the thermal radiation from a hot source occurs at a wavelength of $11 \times {10^{ - 5}}cm$. According to Wein's law, the temperature of the source (on Kelvin scale) will be $n$ times the temperature of another source (on Kelvin scale) for which the wavelength at maximum energy is $5.5 \times {10^{ - 5}}cm$. The value $n$ is
A black body radiates $ 20\,W$ at temperature ${227^o}C$. If temperature of the black body is changed to ${727^o}C$ then its radiating power will be ..... $W$
A black metal foil is warmed by radiation from a small sphere at temperature $T$ and at a distance $d$. It is found that the power received by the foil is $`P$ '. If both the temperature and the distance are doubled, the power received by the foil will be
If the sun’s surface radiates heat at $6.3 \times {10^7}W{m^{ - 2}}$. Calculate the temperature of the sun assuming it to be a black body $(\sigma = 5.7 \times {10^{ - 8}}W{m^{ - 2}}{K^{ - 4}})$