Instruments used to measure the temperature

There are different kinds of thermometers.The bulb of the thermometer contains
alcohol or mercury.When the bulb of the thermometer is immersed in something hot,the bulb gets heated and the liquid in the bulb expands.
Then the liquid rises through the capillary tube in the thermometer.According to the level of rise,the temperature is measured.
The clinical thermometer is used to measure the body  temperature.There is a constriction in the cappilary tube close to the bulb.As the temperature rises,the force of the expansion pushes the mercury up the tube through the constriction does not allow coloumn of mercury to return to the bulb.
Thus,remaining the mercury coloumn stationary in the capillary tube,allowing to get the reading.To reset the thermometer it must be sw
ung sharply.