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General
Easy
Question
A conductor having conductivity ' k ' and whose radius varies linearly with length L is as shown is figure
The radius of a conductor having uniform cross sectional area which gives same thermal resistance as the given conductor for same length with same conductivity is
The correct answer is:
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A linear rod of length L and uniform cross section area A is having thermal conductivity, which varies along its length as, 
where 
is measured from one of its ends as shown in figure. The two ends of the rod are maintained at temperatures of 
and 
, the rate at which heat flows at steady state is
A linear rod of length L and uniform cross section area A is having thermal conductivity, which varies along its length as, where is measured from one of its ends as shown in figure. The two ends of the rod are maintained at temperatures of and , the rate at which heat flows at steady state is
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Two solid spheres of same material but diameters in the ratio of 5:4 are at temperatures 227°C and 127°C respectively. The temperature of the surrounding is 27°C and Stefan's law holds. Calculate the ratio of rates of loss of heat of the two spheres?
Two solid spheres of same material but diameters in the ratio of 5:4 are at temperatures 227°C and 127°C respectively. The temperature of the surrounding is 27°C and Stefan's law holds. Calculate the ratio of rates of loss of heat of the two spheres?
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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.
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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 
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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 
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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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