On heating one end of a rod, the temperature of whole rod will be uniform when

Temperature difference of $120\,^oC$ is maintained between two ends of a uniform rod $AB$ of length $2L$. Another bent rod $PQ$, of same cross-section as $AB$ and length $\frac{{3L}}{2}$,  is connected across $AB$ (See figure). In steady state, temperature difference between $P$ and $Q$ will be close to .......... $^oC$

Four identical rods of same material are joined end to end to form a square. If the temperature difference between the ends of a diagonal is ${100^o}C$, then the temperature difference between the ends of other diagonal will be ........ $^oC$

Three rods made of the same material and having same cross-sectional area but different lengths $10\, cm, 20\, cm$ and $30\, cm$ are joined as shown. The temperature of the junction is......... $^oC$ 

A rod of length $L$ and uniform cross-sectional area has varying thermal conductivity which changes linearly from $2K$ at endAto $K$ at the other end $B$. The endsA and $B$ of the rod are maintained at constant temperature $100^o C$ and $0^o C$, respectively. At steady state, the graph of temperature : $T = T(x)$ where $x =$ distance from end $A$ will be

In the Arctic region, hemispherical houses called Igloos are made of ice. It is possible to maintain a temperature inside an Igloo as high as $20^{\circ} C$ because