Two rods of the same length and material transfer a given amount of heat in 12 s , when they are joined end to end, i.e. in series. When they are joined in parallel, they will transfer the same heat under the same conditions in

Step-by-step solution

∆ t = ∆ Q ∆ x KA ∆ T When two rods of same length are joined in parallel, A   → 2   and   ∆ x → 1 2   times ∴   ∆ t   becomes 1 4   times   i . e . , 1 4 × 12   s = 3   s