Question

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 $^{\text{o}}{\text{C}}$ because.
A) Ice has high thermal conductivity
B) Ice has low thermal conductivity
C) Ice has high specific heat
D) Ice has higher density than water

Answer 1

Hint: Actually Igloos work on the concept of thermal conductivity of the walls of Igloo which are made from ice. Also link the conductivity of Igloo ice with conductivity of air.

Complete step-by-step answer:
Basically, Igloos are made up of the compressed Ice not from randomly picked up solid ice. Compressed ice can be used as building blocks of the Igloo means these Ice blocks are used as the bricks for Igloo construction.
Igloo maintains its temperature by means of thermal conductivity. Igloo lower its thermal conductivity by two methods:

(i) By trapping air in bricks of it: As the compressed Ice is used as a brick block of the Igloo. It has two reasons, firstly it is easy to build igloo with compressed air and second is that compressed ice bricks trap air in it. As compared to solid ice, the compressed ice contains 95% more air in it. And air is the bad conductor of heat. So this air trapped maintains high temp inside the Igloo by reducing the thermal conductivity of the walls of the Igloo.

(ii) By maintaining minimum temp difference: The thermal conductivity also depends on the temperature difference between two mediums. As the heat transfer between two mediums can be basically given as
${Q = k\Delta T}$ ………. (i)
Where ${\Delta T}$= temperature difference
$Q$= heat transferred
$K$= thermal constant
So, in case of igloo the temp of the wall of igloo is almost equal to the surrounding temperature. Hence the temperature difference is very low as a result the heat transfer from igloo to surrounding will be very less.

$\therefore$ Igloo works on low thermal conductivity. Option (B) is correct.

Note: In a special type of igloo to maintain high temperature inside it. The heat sink method is used. In which uppermost part of igloo used for living, middle part used for fire burning and lowermost part is used as heat sink.