A cylinder of radius R and conductivity K 1 = 100 W m − 1 K − 1 is surrounded by a coaxial shell of inner radius R and outer radius 2 R and conductivity K 2 = 20 . The ends of the system are held

Question

A cylinder of radius R and conductivity K 1 ​ = 100 W m − 1 K − 1 is surrounded by a coaxial shell of inner radius R and outer radius 2 R and conductivity K 2 ​ = 20 . The ends of the system are held at two temperatures. Find the effective conductivity in W m − 1 K − 1 .

TestHub · Accepted Answer

The two are in parallel. Areas: π R 2 and π ( 4 R 2 − R 2 ) = 3 π R 2 . K e ff ​ = 4 100 × 1 + 20 × 3 ​ = 40 .

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