Thermal Properties of Matter

A black body is at a temperature of $\text{5760}\text{K.}$ The energy of radiation emitted by the body at wavelength $\text{250}\text{nm}$ is $U_{1}$, at wavelength $\text{500}\text{nm}$ is $U_{2}$ and that at…

Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are $K_{1}$ and $K_{2}$. The thermal conductivity of the composite rod will be

The quantities of heat required to raise the temperature of two solid copper spheres of radii $r_{1}$ and $r_{2}\left(r_{1}=1.5r_{2}\right)$ through $1K$ are in the ratio:

A spherical black body with a radius of $12\mathrm{cm}$ radiates $450W$ power at $500K$. If the radius were halved and the temperature doubled, the power radiated in watt would be

The power radiated by a black body is P and it radiates maximum energy at wavelength, $\lambda\,_{0}$. If the temperature of the black body is now changed so that it radiates maximum energy at wavelength…

A water heater of power $2000W$is used to heat water. The specific heat capacity of water is $4200J\mathrm{kg}^{-1}K^{-1}$. The efficiency of heater is $70%$. Time required to heat $2\mathrm{kg}$ of water from…

The heat extracted out of $x$ gram of water initially at $50^{\circ}C$ to cool it down to $0^{\circ}C$ is sufficient to evaporate $(1000 - x)$ gram of water also initially at $50^{\circ}C$. The value of $x$ (closest…

A block of ice at $-10^{\circ}C$ is slowly heated and converted to steam at $100^{\circ}C$. Which of the following curves represent the phenomenon qualitatively:

A block of ice of mass $120g$ at temperature $0^{\circ}C$ is put in $300g$ of water at $25^{\circ}C$. The $xg$ of ice melts as the temperature of the water reaches $0^{\circ}C$. The value of $x$ is [Use: Specific heat…

A brass wire of length 2 m and radius 1 mm at $27^{\circ} \mathrm{C}$ is held taut between two rigid supports. Initially it was cooled to a temperature of $-43^{\circ} \mathrm{C}$ creating a tension $T$ in the wire. The…

Two conductors have the same resistances at$0^{\circ}C$but their temperature coefficients of resistance are$\alpha_{1}$and$\alpha_{2}$. The respective temperature coefficients for their series and parallel combinations…

A bowl filled with very hot soup cools from$98^{\circ}C$to $86^{\circ} \mathrm{C}$ in 2 minutes when the room temperature is $22^{\circ} \mathrm{C}$. How long it will take to cool from $75^{\circ} \mathrm{C}$ to…