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A rod of 40 cm in length and temperature...

A rod of 40 cm in length and temperature difference of `80^(@)C` at its two ends. Another rod B of length 60cm and of temperature difference `90^(@)C`, having the same area of cross-section. If the rate of flow of heat is the same, then the ratio of their thermal conductivities will be

A

`3 : 4`

B

`4 : 3`

C

`1 : 2`

D

`2 : 1`

Text Solution

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The correct Answer is:
A
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Knowledge Check

  • The ratio of the diameters of two metallic rods of the same material is 2 : 1 and their lengths are in the ratio 1 : 4 . If the temperature difference between their ends are equal, the rate of flow of heat in them will be in the ratio

    A
    `2 : 1`
    B
    `4 : 1`
    C
    ` 8 : 1`
    D
    `16 : 1`

  • Wires A and B have have identical lengths and have circular cross-sections. The radius of A is twice the radius of B i.e. R_A = 2R_B . For a given temperature difference between the two ends, both wires conduct heat at the same rate. The relation between the thermal conductivities is given by-

    A
    `K_(A)=4K_(B)`
    B
    `K_(A)=2K_(B)`
    C
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    D
    `K_(A)=K_(B)//4`

  • The ratio of thermal conductivity of two rods of different material is 5 : 4 . The two rods of same area of cross-section and same thermal resistance will have the lengths in the ratio

    A
    `4 : 5`
    B
    `9 : 1`
    C
    `1 : 9`
    D
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