Correct Answer - A
(a) Given `H_I=H_(II)`
`k_1(ADeltaT)/(l+l)xxt_1=k_2((A+A)DeltaT)/lxxt_2`
`:. T_2=(k_1)/(k_2)xx(t_1)/4…….(i)`
Where `k_1 and k_2` are the equivalent conductivities in
configuration I and II respectively.
For configuration I:
`(l+l)/(k_1)=l/K+l/(2K) :. 2/(K_1)=3/(2k)`
`:. K_1=(4k)/3.....(ii)` For configuration II:
`k_2(A+A)=kA+2kA`
`:. k_2=(3k)/2......(iii)`
From (i) , (ii)and (iii) `t_2=((4k)/3)/((3k)/2)xx9/4=2sec`
option (a) is correct