The device which is used for measuring the temperature of a body is called a thermometer.

The types of thermometer used in our daily life and their working principles are:

1.Clinical Thermometer (Mercury and Alcohol)

Clinical thermometers, which include both mercury and alcohol as thermometric liquids, are designed specifically for measuring human body temperature.

Working principle of clinical thermometer:

This thermometer consists of a glass tube filled with thermometric liquid. As the body temperature increases, the liquid expands and rises in the tube. The level of liquid indicates the temperature on a calibrated scale.

2.Digital Thermometer

Working principle:

Digital thermometers use electronic sensors to measure temperature. When placed in contact with the body (oral, rectal, or underarm), the sensor detects the temperature and displays it numerically on a digital screen. They provide quick and accurate readings.

3. Infra-red Thermometer

Working principle:

The thermometer has a lens to focus infrared light from any object in front of its sensor called thermopile. The thermopile absorbs infrared radiation and turns it into heat. The more infrared energy, the hotter the thermopile gets. This heat is turned into electricity. The electricity is sent to a detector, which uses it to determine the temperature of any object it is pointed at.