Question

how is temperature measured with a thermometer

Answer 1

Temperature is measured with the thermometer usually made up of a glass tube with coloured alcohol.
Thermometer has two important elements which helps to measure temperature:-
1.) a sensor which responded to temperature change.
2.) a means of converting the sensor response into values of temperature.

Answer 2

Answer:

A thermometer measures temperature through a glass tube sealed with mercury that expands or contracts as the temperature rises or falls. ... As temperatures rise, the mercury-filled bulb expands into the capillary tube. Its rate of expansion is calibrated on the glass scale.