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Calculate the thermal resistance of the hollow frustum for the terminals shown, ie the inner and outer surfaces of the hollow frustum...

Assume conductivity to be 1.

22 comments:

  1. very complicated ans

    ln((a+b)/a)
    ----------- (whole divided by)
    2pi[L^2+(b-a)^2]

    [] stands for sqr root

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  2. pendi bhaiya....
    i am not able to solve this ques...
    plz help me....

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  3. ln(3a/a+b)
    ----------- (whole divided by)
    2pi[L^2+(b-a)^2]

    if this is wrong then plz telll me
    is the curved surface area of frustrum l(r+R) ; where l is slant ht???

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  4. ankush...u can urself derive that...i just did....it is the same....only that u have to multiply that by pi..

    my answer...
    (2log2)/pi[h^2 + (b-a)^2]

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  5. the answer of the previous hollow frustum problem is L/6pi ,and i am 100 percent confident....... ANUJ SIR PLEASE TELL THE CORRECT ANSWER .........

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  6. let me give you a few hints:

    1)assume the current flow to be perpendicular to the axis of symmetry of the hollow frustum..

    2)try to visualize it as a combination of cylinders.

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  7. to the previous problem, your ans. was right.

    this hint was for this question.

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  8. did no one else get this answer???
    cmon people..its a parallel combination..

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  9. looking at ur hints.......

    do u mean we take a cylinder whose centre is at a distance x from smaller base
    whose radii are

    a+(b-a)x/l
    and
    a+b/2+(b-a)x/l

    and integrate??
    but it wud involve integration of dx/(ln x)

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  10. amritpal's last ans. was correct.
    to integrate, you need the resistance of a hollow cylinder b/w inner and outer radii..

    ankush, inner radius is a/2+(b/2-a/2)x/L

    outer radius is twice this..

    maybe i commented on the inner radius of the left end somewhere...

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