Question

• Explain the role of mercury in the thermometer
• Can we use water instead of mercury

Answer 1

Answer

$\bigstar$ Role of mercury :-

• Mercury is present in the bulb of the thermometer. Whenever, the bulb comes in contact with a hot object, the mercury gets heated and expands quickly. It always moves upwards in the narrow tube of the thermometer.
• On coming in contact with a cold object, it contacts and moves downwards. It is so smooth so that it does'nt stick into the wall of the thermometer. When kept the downwards it doesn't goes back because of the bend near it's bulb which is called kink.

$\bigstar$ Use of water instead of mercury :-

• No, we cannot use the water instead of mercury in a thermometer because it doesn't expand or contrast as much as mercury does on heating or cooling.
• Moreover, the water will stick to the walls of the thermometer whereas, the mercury doesn't stick to it's walls.