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Important questions on Conduction

HARD

Two rods of the same length and diameter having thermal conductivities  are joined in parallel. The equivalent thermal conductivity of the combination is:

A

B

C

D

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HARD

The heat capacity of a metal is 4200 J/k. Its water equivalent is-

A

B

C

D

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HARD

State and explain the laws of thermal conductivity.

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MEDIUM

A cylinder of radius  made of a material of thermal conductivity is surrounded by a cylindrical shell of inner radius  and outer radius made of a material of thermal conductivity . The two ends of the combined system are maintained at two different temperatures. There is no loss of heat across the cylindrical surface and the system is in steady state. The effective thermal conductivity of the system is?

This question has multiple correct options
A

B

C

D

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HARD

Define the term 'conductivity' of a metallic wire. write its SI unit.

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HARD

On the average, the temperature of the earth' s crust increases for every 30 m of depth. The average thermal conductivity of the earth's crust is 0.75 J/m s K. Solar constant is . Match the items in Column I with that in Column II:

List 1i. Heat lost by the core of the earth per second due to conduction (in W)ii. Heat received by the earth per second from the sun (in W)ii. If e = 1, average surface temperature of the earth in equilibrium (in K)iv. Ratio of heat lost by the earth to the heat received from the sun
List 2276$$7.5 \times 10^{-5}$$$$1.3 \times 10^{13}$$$$1.7 \times 10^{17}$$
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HARD

A cylindrical rod of length 50 cm and cross-sectional area is fitted between a large ice chamber at and an evacuated chamber maintained at `as shown in figure only small portions of the road are inside the chambers and the rest is thermally insulated from the surrounding. the cross-section going into the evacuated chamber is blackened so that it completely absorbs any radiation falling on it. the temperature of the blackened end is when steady state is reached.seftan constant find the thermal conductivity of the material of the rod.

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HARD

A hollow metallic sphere of radius 20 cm surrounds a concentric metallic sphere of radius 5 cm.the space between the two spheres is filled with a nonmetallic material. the inner and outer sphere are maintained at and respectively and it is found that 100 J of heat passes from the inner sphere to the outer sphere per second. find the thermal conductivity of the material between the spheres.

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HARD

Two rods A and B of same length and radius are joined together. the thermal conductivity of A and B are and . Under steady state conditions, if the temperature difference between the open ends of A and B is , the temperature difference across 'A' is:

A

B

C

D

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HARD

A slab of stone area and thickness is exposed on the lower surface to steam at . A block of ice at rests on upper surface of the slab. In one hour of ice of melted. The thermal conductivity of the stone is is
(Latent heat of ice )

A

B

C

D

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