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General
Easy
Question
A cylinder of radius R and length l is made up of a substance, whose thermal conductivity K varies with the distance 
from the axis as 
Deter mine the effective thermal conductivity between the flat faces of the cylinder.
The correct answer is:
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Two rods(One semi - circular and other straight) of same material and of same cross -sectional area are joined as shown in the figure. The points A and B are maintained at different temperatures. Find the ratio of the heat transferred through a cross - section of a semi - circular rod to the heat transferred A through a cross section of the straight rod in a given time.
Two rods(One semi - circular and other straight) of same material and of same cross -sectional area are joined as shown in the figure. The points A and B are maintained at different temperatures. Find the ratio of the heat transferred through a cross - section of a semi - circular rod to the heat transferred A through a cross section of the straight rod in a given time.
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Four identical rods AB,CD,CF and DE are connected as shown in figure. The length, cross- sectional area and thermal conductivity of each rod are L,A, K respectively. The ends A, E, F are maintained at temperature 
and 
respectively. Assuming no loss of heat to the atmosphere, calculate the temperature at B [CB = BD].
Four identical rods AB,CD,CF and DE are connected as shown in figure. The length, cross- sectional area and thermal conductivity of each rod are L,A, K respectively. The ends A, E, F are maintained at temperature and respectively. Assuming no loss of heat to the atmosphere, calculate the temperature at B [CB = BD].
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Figure shows a cylinder of cross sectional area A and total length 4 L, containing 
moles of oxygen each at temperature 
and 
are separated by a fixed piston of length 2 L and thermal conductivity K. Find the rate of heat flow through the piston after time 
. (Given 
)
Figure shows a cylinder of cross sectional area A and total length 4 L, containing moles of oxygen each at temperature and are separated by a fixed piston of length 2 L and thermal conductivity K. Find the rate of heat flow through the piston after time . (Given )
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Solid copper cube of edge 1 cm is suspended an evacuated enclosure. Its temperature is found to fall from 100°C to 99°C in 100 seconds. Another solid copper cube of edge 2 cm with similar surface nature is suspended in similar manner. Find the time required for this cube to cool from 100°C to 99°C.
Solid copper cube of edge 1 cm is suspended an evacuated enclosure. Its temperature is found to fall from 100°C to 99°C in 100 seconds. Another solid copper cube of edge 2 cm with similar surface nature is suspended in similar manner. Find the time required for this cube to cool from 100°C to 99°C.
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The graph shown give the temperature along x-axis that extends directly through a wall consisting of three layers A, B and C. The air temperature on one side of the wall differ from that on the other side. Thermal conduction through the wall is steady. Out of the three layers A, B and C thermal conductivity is greatest for layer
The graph shown give the temperature along x-axis that extends directly through a wall consisting of three layers A, B and C. The air temperature on one side of the wall differ from that on the other side. Thermal conduction through the wall is steady. Out of the three layers A, B and C thermal conductivity is greatest for layer
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No heat flows through the central rod of conductivity 
in the arrangement of five identical rods of different conductivity 
and 
Temperature are constant at 
and at 
then
No heat flows through the central rod of conductivity in the arrangement of five identical rods of different conductivity and Temperature are constant at and at then
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Three - rods AB, BC and BD made of the same cross-section have been joined as shown in figure. The ends A, C and D are held at temperatures of 20°C, 80°C, and 80°C respectively . If each rod is of same length, then the temperature at the junction B of the three rods is :
Three - rods AB, BC and BD made of the same cross-section have been joined as shown in figure. The ends A, C and D are held at temperatures of 20°C, 80°C, and 80°C respectively . If each rod is of same length, then the temperature at the junction B of the three rods is :
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Two slabs A & B having lengths 
and 
, respectively, and same cross - section have thermal conductivities 
and 
respecitvely. They are placed in contact and a constant temperature difference is maintained across the combination. The ratio of the quantities of heat flowing through A and B in a given time is
Two slabs A & B having lengths and , respectively, and same cross - section have thermal conductivities and respecitvely. They are placed in contact and a constant temperature difference is maintained across the combination. The ratio of the quantities of heat flowing through A and B in a given time is
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The rate of emission of radiation of a black body at temperature 27°C is 
If its temperature is increased to 327°C the rate of emission of radiation is 
The relation between 
and 
is
The rate of emission of radiation of a black body at temperature 27°C is If its temperature is increased to 327°C the rate of emission of radiation is The relation between and is
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A gas is expanded from volume 
to 2 under three different processes. Process 1 is isobaric process, process 2 is isothermal and process 3 is adiabatic. Let 
and 
, be the change in internal energy of the gas is these processes. Then :–
A gas is expanded from volume to 2 under three different processes. Process 1 is isobaric process, process 2 is isothermal and process 3 is adiabatic. Let and , be the change in internal energy of the gas is these processes. Then :–
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From the following V–T diagram we can conclude:–
From the following V–T diagram we can conclude:–
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Four containers are filled with monoatomic ideal gases. For each container, the number of moles, the mass of an individual atom and the rms speed of the atoms are expressed in terms of n, m and 
respectively. If 
and 
are their temperatures respectively then which one of the options correctly represents the order ?
Four containers are filled with monoatomic ideal gases. For each container, the number of moles, the mass of an individual atom and the rms speed of the atoms are expressed in terms of n, m and respectively. If and are their temperatures respectively then which one of the options correctly represents the order ?
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Two identical glass bulbs are interconnected by a thin glass tube at 
. A gas is filled at N.T.P. in these bulb is placed in ice and another bulb is placed in hot bath, then the pressure of the gas becomes 1.5 times. The temperature of hot bath will be :–
Two identical glass bulbs are interconnected by a thin glass tube at . A gas is filled at N.T.P. in these bulb is placed in ice and another bulb is placed in hot bath, then the pressure of the gas becomes 1.5 times. The temperature of hot bath will be :–
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The expansion of unit mass of a perfect gas at constant pressure is shown in the diagram. Here:–
The expansion of unit mass of a perfect gas at constant pressure is shown in the diagram. Here:–
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Pressure versus temperature graphs of an ideal gas are as shown in figure. Choose the wrong statement:–
Pressure versus temperature graphs of an ideal gas are as shown in figure. Choose the wrong statement:–
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