A body cools in a surrounding which is at a constant temperature of $\theta _0$ . Assuming that it obeys Newton's law of cooling, its temperature $\theta $ is plotted against time $t$ . Tangents are drawn to the curve at the points $A(\theta = \theta _1)$ and $B(\theta = \theta _2)$ . These tangents meet the time-axis at angles $\alpha _1$ and $\alpha _2$ as shown in the graph then
$\frac{{\tan \,{\alpha _1}}}{{\tan \,{\alpha _2}}} = \frac{{{\theta _2}}}{{{\theta _1}}}$
$\frac{{\tan \,{\alpha _1}}}{{\tan \,{\alpha _2}}} = \frac{{{\theta _1}}}{{{\theta _2}}}$
$\frac{{\tan \,{\alpha _1}}}{{\tan \,{\alpha _2}}} = \frac{{{\theta _1} - {\theta _0}}}{{{\theta _2} - {\theta _0}}}$
$\frac{{\tan \,{\alpha _1}}}{{\tan \,{\alpha _2}}} = \frac{{{\theta _2} - {\theta _0}}}{{{\theta _1} - {\theta _0}}}$
The temperature of furnace is $200\,^oC$, in its spectrum the maximum intensity is obtained at about $400\,\mathop A\limits^o $, If the maximum intensity is at $200\,\mathop A\limits^o $. Calculate the temperature of the furnace in ${}^oC$. ......... $^oC$
Gravitation force is required for
The radiant energy from sun incident normally at the surface of earth is $20\, kcal/m^2-min$. What would have been the radiant energy incident normally on the earth if the sun had a temperature twice of the present one ......... $kcal/m^2-min$
Two rods are connected as shown. The rods are of same length and same cross sectional area. In steady state, the temperature $\left( \theta \right)$ of the interface will be........ $^oC$
The rate of dissipation of heat by a black body at temperature $T$ is $Q$. What will be the rate of dissipation of heat by another body at temperature $2\,T$ and emissivity $0.25$ ?