Q. A slender rod of length L, diameter d ( L >> d ) and thermal conductivity k1 is joined with another rod of identical dimensions, but of thermal conductivity k2 , to form a composite cylindrical rod of length 2L . The heat transfer in radial direction and contact resistance are negligible. The effective thermal conductivity of the composite rod is
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![Determine the correctness (or otherwise) of the following Assertion [A] and the Reason [R]](https://www.gkseries.com/blog/wp-content/uploads/2023/10/Determine-the-correctness-or-otherwise-of-the-following-Assertion-A-and-the-Reason-R.jpg)
