Question

why there is no kink in laboratory thermometer

Answer 1

The kink or bend in a thermometer helps the mercury to stay at the same level for a few time an does let it to come down fast. So, in clinical thermometer the doctor has to observe the temperature after taking it from the patient, so it should not come down fast and hence it has kink. But in laboratory, the temperature changes continuously and so there doesn't require any kink to retain readings. 

Answer 2

Kink also is called a constriction .

⊕ Constrictions present in a thermometer are used for the following

О Constrictions prevent the level of the thermometric liquid to suddenly fall after measuring the temperature.

О The constriction hence conserves the reading of the thermometer for a certain period of time after which it falls .

О This allows the user to get enough time to read the readings of the level of the thermometer.

Θ Kink is not present in lab thermometers

ОThe absence of constrictions help to measure the temperature readings accurately .

О In a laboratory the thermometer is generally required for measuring different instances of a chemical reaction

О The chemical reaction may change the temperatures very abruptly.

О Thus constrictions should interrupt the accurate and rapid changes in the thermometer.

О This also helps to read temperature in liquids because the temperature should rapidly change in such a case.

→ That's why kink is not present in laboratory thermometer

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