Mercury does not fall or rise in a clinical thermometer when taken out from the mouth because of the KINK present in it.
When the mercury stops rising in a thermometer, the level reached is read off a scale etched on the glass tube. This shows the temperature of the hot water. There is little point in reading the scale until it stops moving.
The constriction prevents the mercury from returning back to the bulb when the thermometer is removed from a particular body.
The kink in a clinical thermometer prevents the column of mercury from falling back down when the thermometer is removed from the patient's body, allowing for an accurate temperature reading to be taken and read.
A mercury thermometer measures temperature based on the expansion or contraction of the liquid mercury inside the narrow tube. As temperature rises, the mercury expands and travels up the tube, indicating a higher temperature, and vice versa. The temperature reading is taken at the point where the mercury level stabilizes.
It contracts.
A clinical thermometer measures the max temp of the human body due to the expansion of the mercury in the bulb, which flows past a kink in the column and rises in the graduated stem, to read the highest body-temp. Once it is removed from the body, the mercury stays at that level, and does not fall because it cannot flow back into the bulb -- the kink prevents the back flow. It has to be shaken vigorously, as you know, for us to get the mercury back; then it is ready to take the temp again.. Also, the temp cannot rise further on its own from the max reading because the mercury does not expand the moment the thermometer is taken out of the body. Incidentally, temp can be measured under the armpits and in the rectum also.
Absolutely, the thermometer is independent of any other measuring device, therefore the actual temperature is dependent on the reading that is taken off the thermometer.
If you have an old thermometer that has mercury, then the shaking makes all of the mercury flow to the bottom of the thermometer. Then, you can get a better reading. The current digital ones work differently. Thermometers used for taking people temperatures are a special kind that go up with heat but don't go down with cold. So you have to shake a thermometer before taking your temperature to make the reading go down below your own temperature. Then the thermometer can go up again to read your temperature.
don't break it. If you do open the windows.
In case of ordinary thermometer if the thermometer is taken out the body whose temperature has been seen, the Mercury would fall down as the bulb gets cooled. But in case of clinical thermometer even after the thermometer has been taken out of the mouth of the patient the level of mercury would be held at the same level though the bulb falls to the room temperature. So doctor could see the temperature liesurely. To bring back the mercury to lowest level we have to give jerks to the thermometer by shaking it.
A Mercury barometer works by expanding and therefore raising the mercury of the barometer, then reading the level up to which the mercury has gone.