Q)
(chatquestion)...temperatures. All heat entering the face A goes out of the end
the sides of the bar. The effective thermal conductivity of the bar is
B there being no loss of heat from
и9
(1) 15K/16
(2) 6K/13
(3) 5K/16
(4) 2K/13.
Q.81 Figure shows three different arrangements of materials 1,2 and 3 to form a wall. Thermal conductivities
are k,>k,>k. The left side of the wall is 20°C higher than the right side. Temperature difference AT
across the material I has following relation in three cases:
3.
(1) AT,>AT,>AT.
(3) AT, =AT, > AT.
(2) AT, = AT, = AT,
(4) AT, = AT, <AT,
Q.82 A 2cm thick slab of commercial thermocole, 100 cm2 in cross-section and having thermal
conductivity 2 x 104 cal sec-l cm- (C°)-! has insulating regions differing by 100°C. The quantity
of heat flowing through it in a day will be -
(1) 20.4 kcal
(2) 43.2 kcal
(3) 86.4 kcal
(4) 63.6 kcal
...
