Two rods of same length & material transfer a given amount of heat in 12 s when they are joined end to end. But when they are joined length wise parallel to each other they will transfer same amount of heat in same condition in time

Step-by-step solution

Let the heat transferred be Q When rods are joined end to end, heat transferred by each rod = Q = KA 2 l 12...(i) When rods are joined lengthwise, Q = K 2 ~A l t ...(ii) From equation (i) and (ii), aligned & K 2 ~A l t = KA 2 l 12 & t = 12 2 2 =3 ~s aligned