Two rods of same length and material are joined end to end. They transfer heat in 8 second. When they are joined in parallel they transfer same amount of heat in same conditions in time

Step-by-step solution

Let R be the thermal resistance of each rod when connected in series, the total resistance will be R _ s =2 R Whey they are connected in parallel, the effective resistance will be aligned & R _ p = R 2 & R _ p R _ s = 1 4 aligned In parallel combination, the resistance becomes one-fourth and hence time will also become one-fourth. Time taken 8 4 =2 ~s