The maximum energy in the thermal radiation from a hot source occurs at a wavelength of $11 \times 10^{-5}\, cm$ . According to Wien'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 of $n$ is
$2$
$4$
$0.5$
$1$
A hot liquid kept in a beaker cools from $80\,^oC$ to $70\,^oC$ in $2\, min$. If the surrounding temperature is $30\,^oC$, then the time of cooling of the same liquid from $60\,^oC$ to $50\,^oC$ ........ $\sec$
Two rods of same length and material transfer a given amount of heat in $12\, seconds$ , when they are joined end to end. But when they are joined in series, then they will transfer same heat in same conditions in........ $\sec$
Which of the following material is most suitable for cooking utensil?
Three copper blocks of masses $M_1, M_2$ and $M_3$ $kg$ respectively are brought into thermal contact till they reach equilibrium. Before contact, they were at $T_1, T_2, T_3(T_1> T_3)$. Assuming there is no heat loss to the surroundings, the equilibrium temprature $T$ is ($s$ is specific heat of copper)
Radiated energy at $TK$ temperature is $E$ for a body of diameter $'d'$. If temperature becomes $(2T)$ and diameter becomes $\frac{d}{4}$ then radiated energy will be :-