A thin paper cup filled with water does not catch fire when placed over a flame. This is because
KVPY 2014, Medium
Download our appand get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Similar Questions
- 1Three conducting rods of same material and cross section are shown in figure. Temperature at $A,D$ and $C$ are maintained at $20\ ^oC, 90\ ^oC$ and $0\ ^oC$. The ratio of lengths of $BD$ and $BC$ if there is no heat. Flows in $AB$ isView Solution
- 2Match the temperature of a black body given in List-$I$ with an appropriate statement in List-$II$, and choose the correct option.View Solution
[Given: Wien's constant as $2.9 \times 10^{-3} \mathrm{~m}-\mathrm{K}$ and $\frac{\mathrm{hc}}{\mathrm{e}}=1.24 \times 10^{-6} \mathrm{~V}-\mathrm{m}$ ]
List-$I$ List-$II$ ($P$) $2000 \mathrm{~K}$ ($1$) The radiation at peak wavelength can lead to emission of photoelectrons from a metal of work function $4 \mathrm{eV}$ ($Q$) $3000 \mathrm{~K}$ ($2$) The radiation at peak wavelength is visible to human eye. ($R$) $5000 \mathrm{~K}$ ($3$) The radiation at peak emission wavelength will result in the widest central maximum of a single slit diffraction. ($S$) $10000 \mathrm{~K}$ ($4$) The power emitted per unit area is $1 / 16$ of that emitted by a blackbody at temperature $6000 \mathrm{~K}$. ($5$) The radiation at peak emission wavelength can be used to image human bones. - 3Wires $A$ and $B$ have identical lengths and have circular cross-sections. The radius of $A$ is twice the radius of $B$ $i.e.$ ${r_A} = 2{r_B}$. For a given temperature difference between the two ends, both wires conduct heat at the same rate. The relation between the thermal conductivities is given byView Solution
- 4$Assertion :$ Woolen clothes keep the body warm in winterView Solution
$Reason :$ Air is a bad conductor of heat. - 5The rectangular surface of area $8$ cm $ \times $ 4cm of a black body at a temperature of ${127^o}C$ emits energy at the rate of $E$ per second. If the length and breadth of the surface are each reduced to half of the initial value and the temperature is raised to ${327^o}C$, the rate of emission of energy will becomeView Solution
- 6View SolutionIf a liquid is heated in weightlessness, the heat is transmitted through
- 7View SolutionIn which case the thermal conductivity increases from left to right
- 8Rate of cooling at $600K$ , if surrounding temperature is $300K$ is $R$ . The rate of cooling at $900K$ isView Solution
- 9An ice box used for keeping eatable cold has a total wall area of $1\;metr{e^2}$ and a wall thickness of $5.0cm$. The thermal conductivity of the ice box is $K = 0.01\;joule/metre{ - ^o}C$. It is filled with ice at ${0^o}C$ along with eatables on a day when the temperature is $30°C$ . The latent heat of fusion of ice is $334 \times {10^3}joules/kg$. The amount of ice melted in one day is ........ $gms$ ($1day = 86,400\;\sec onds$)View Solution
- 10In the Ingen Hauz’s experiment the wax melts up to lengths $10$ and $25 cm$ on two identical rods of different materials. The ratio of thermal conductivities of the two materials isView Solution