Suppose that water is used in a thermometer instead of mercury. If the temperature is at 4°C and then changes, why can’t the thermometer indicate whether the temperature is rising or falling?
Solution Step 1 of 2 Thermometers measure temperature by the shrinkage and expansion of the working fluid inside the thermometer. When we use water has the working fluid. Since at 4 c the water has maximum density , any 0 0 change in temperature from 4 c will result in the expanding of the water. Therefore after 4 c it will rise if it cools or rise even if is heated. So past 4 c , it would only move up, even when we want that to move down for cooling and move upward for heating. So the water filled 0 thermometer at 4 c would expand as the water is cooled or heated.
