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1.56 × 10^5 J of heat is conducted throu...

`1.56 × 10^5 J` of heat is conducted through is `2 m^2` wall of 12 cm thick in one hour. Temperature difference between the two sides of the wall is `20 ^@C.` The thermal conductivity of the material of the wall is (in `Wm ^(-1) K^(-1)`)

A

`0.11`

B

`0.13`

C

`0.15`

D

`1.2`

Text Solution

Verified by Experts

The correct Answer is:
B
Rate of heat flow through the wall is
`(Delta Q)/(Delta t) =(KA Delta T)/( t)`
Subtitiing the given values we get
` (1.56 xx 10^5 J )/(3600 s ) = (K xx 2 m^2 xx 20 ^@ C )/( 12 xx 10^(-2) m)`
`k=( 1.56 xx 10^5 xx 12 xx 10^(-2))/( 3600 xx 2xx 20 ) W m^(-1) K^(-1)`
` = ( 1.56 )/(12) W m^(-1) K^(-1) = 0.13 W m^(-1) K^(-1)`
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Knowledge Check

  • 1.56 xx 10 ^(5) J of heat is conducted through a 12 cm thick wall of area 2 m ^(2) in one hour. If the temperature difference between the two sides of the wall is 20 ^(@)C, then the thermal conductivity (in W m-^(1) K^(-1)) of the material of the wall is

    A
    0.11
    B
    0.13
    C
    0.15
    D
    1.2

  • If the temperature difference on the two sides of a wall increases from 100^@C to 200^@C , its thermal conductivity

    A
    remains unchanged
    B
    is doubled
    C
    is halved
    D
    becomes four times

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