A cup of tea cools from $65.5^o C to 62.5 ^o C$ in one minute in a room of $22.5 ^o C$. How long will the same cup of tea take, in.............. minutes, to cool from $46.50^o C to 40.5 ^o C$ in the same room ? (choose nearest value)
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Radiation from a black body at the thermodynamic temperature $T_1$ is measured by a small detector at distance $d_1$ from it. When the temperature is increased to $T_2$ and the distance to $d_2$ , the power received by the detector is unchanged . What is the ratio $d_2/d_1$ ?
A black body at $200 K$ is found to exit maximum energy at a wavelength of $14\mu m$. When its temperature is raised to $1000K$ , the wavelength at which maximum energy is emitted is
Twelve conducting rods form the riders of a uniform cube of side $'l'.$ If in steady state, $B$ and $H$ ends of the rod are at $100^o C$ and $0^o C$. Find the temperature of the junction $'A'$ ....... $^oC$
A spherical black body with a radius of $12\ cm$ radiates $450\ watt$ power at $500\ K$. If the radius were halved and the temperature doubled, the power radiated in watt would be
Three rods made of the same material and having the same cross section have been joined as shown in the figure. Each rod is of the same length. The left and right ends are kept at ${0^o}C$ and ${90^o}C$ respectively. The temperature of the junction of the three rods will be ...... $^oC$
A tungsten body of diameter $2.3\, cm$ is at $2000\,^oC$. It radiates $30\%$ of the energy radiated by a black body of same radius and temperature. Find radius of black body which will radiate energy at same rate at the same temperature......... $cm$
Star $A$ has radius $ r$ surface temperature $T$ while star $B$ has radius $4r$ and surface temperature $T/2$ . The ratio of the power of two starts, $P_A : P_B$ is
The temperature of a body falls from ${50^o}C$to ${40^o}C$ in $10$ minutes. If the temperature of the surroundings is ${20^o}C$ Then temperature of the body after another $10$ minutes will be ........ $^oC$