In the two-insulator experiment, which outcome indicates the better insulator?

• A. The small can has the higher temperature over the fixed period
• B. The small can has the lower temperature over the fixed period
• C. The larger can stays cooler than the small can
• D. Temperature readings are identical for both insulators

Answer: (A)

The thing being tested is how well insulation slows down heat loss. A better insulator keeps the contents warmer for longer because it reduces the rate at which heat flows from the inside to the surroundings. If, over a fixed period, the small can stays at a higher temperature, that means heat is being lost more slowly from it than from the other can. In other words, the small can’s insulating material is better at reducing heat transfer, so it retains heat more effectively. The other outcomes would mean faster cooling or no difference, which don’t indicate better insulation.