Because the pressure of air may be greater than the pressure of the ascending Mercury.
thermometer consisting of mercury contained in a bulb at the bottom of a graduated sealed glass capillary tube marked in degrees Celsius or Fahrenheit; mercury expands with a rise in temperature causing a thin thread of mercury to rise in the tube
A Mercury thermometer measures temperature by relying on the expansion and contraction of the liquid mercury inside the glass tube. As the temperature changes, the mercury expands or contracts, causing it to rise or fall in the tube, indicating the temperature.
Mercury does not rise in a lab thermometer if there is air in the glass tube because the presence of air creates pressure within the tube that opposes the expansion of the mercury. Without a vacuum, the air pressure prevents the mercury from moving freely up the tube in response to changes in temperature.
A typical mercury thermometer consists of a glass tube with a bulb at one end filled with mercury. As the temperature changes, the mercury expands or contracts, causing it to rise or fall in the tube. The temperature is then read based on the level of the mercury within the graduated scale on the tube.
mercury
either mercury or alcohol
a clinical thermometer consists of mercury(Hg) concealed inside a glass tube with a bulb at the bottom. the bulb portion has the mercury and is thermo-sensitive. owing to the rise in temperature, when kept under the tongue of a patient, the mercury rises over the calibrated tube portion.
Mercury does not fall or rise in a clinical thermometer when taken out from the mouth because of the KINK present in it.
A liquid-in-glass thermometer is a type of thermometer that consists of a glass tube filled with a liquid, typically mercury or alcohol, which expands or contracts with changes in temperature. The level of the liquid in the tube corresponds to the temperature, allowing for temperature measurement.
The thermometer is a sealed glass tube containing mercury in a vacuum. The mercury column will rise or fall due to expansion, and the level is read off a temperature scale.
The mercury in a thermometer rises because of thermal expansion. When the temperature surrounding the thermometer increases, the molecules of the mercury expand, causing it to move up the narrow tube of the thermometer.
MERCURY