A black body, at a temperature of $227\,^oC$ radiates heat at a rate of $7\, cal\, cm^{-2} \,s^{-1}$. At a temperature of $727\,^oC$, the rate of heat radiated in the same $units$ will be ..... $unit$
$80$
$60$
$50$
$112$
If the temperature of the sun were to increase from $T$ to $2T$ and its radius from $R$ to $2R$, then the ratio of the radiant energy received on earth to what it was previously will be
Two ends of roads of length $L$ and radius $r$ of the same material are kept at the same temperature which of the following rod conducts most heat?
Hot water cools from $60\,^oC$ to $50\,^oC$ in the first $10\, min$ and to $42\,^oC$ in the next $10\, min$. The temperature of the surrounding is ........ $^oC$
Six identical conducting rods are joined as shown in figure. Points $A$ and $D$ are maintained at temperatures $200\,^oC$ and $20\,^oC$, respectively. the temperature of junction $B$ will be ........ $^oC$
Which of the following material is most suitable for cooking utensil?