When a mercury thermometer is warmed, the mercury level momentarily goes down before it rises. Can you give an explanation for this?
Solution 46E Introduction If heat is added to a substance, the molecules gain more thermal energy so it will move faster. The molecules/atoms in the substance need more space when it gains more energy. So, the substance will expand and it will take more space. Step 1 When the mercury thermometer is warmed, the glass bulb which contains the mercury will get heated up first. Due to this, the molecules in the glass bulb will vibrate faster and as a result, the glass tube will expand. So, the level of the mercury will go down before it gets heated up. Later, the mercury will get heated up by receiving the heat from the glass tube and it will start to expand. Conclusion If the mercury thermometer is warmed, the mercury level will momentarily go down due to the expansion of glass bulb/container which contains the mercury.