A composite plane wall is made up of two different materials of the same thickness and having thermal conductivities of k1 and k2 respectively. the equivalent thermal conductivity of the slab is (IES-00)
(a)$k_1+k_2$ (b)$k_1k_2$
(c)$\frac{k_1+k_2}{k_1k_2}$ (d)$2\tfrac{k_1k_2}{k_1+k_2}$
Direction: Each of the next consists of two statements, one labeled as the ‘Assertion (A)’ and the other as ‘Reason (R)’. You are to examine these two statements carefully and select the answers to these items using the codes given below:
(a) Both A and R are individually true and R is the correct explanation of A.
(b) Both A and R are individually true but R is not the correct explanation of A.
(c) A is true but R is false
(d)) A is false but R is true
