How Does a Body Thermometer Work?

The body is typically around 98.6 degrees Fahrenheit. The body's temperature is generated by the friction of blood flow from the heart and through the circulatory system. When a person has a fever, heat stroke or other medical ailments, the body's reactions can cause the temperature to rise. When the thermometer is placed in the mouth, the heat in the mouth reports the body's overall temperature. The heat then begins to warm up the mercury in the bulb of the thermometer. As it heats up, the mercury's volume increases, causing it to rise in the tube/capillary. The thermometer is normally allowed to stay in the mouth around two to three minutes for a good reading.

Digital or electronic thermometers function on the use of a sensor at the end of the device, which reads the temperature of the body. The heat is then recorded and sent to a micro-sized computer component within the wider portion of the thermometer. The reading is then translated and reported through the visual screen. While digital body thermometers are considered much faster and even more accurate than their mercury-based relations, the liquid thermometers are still more commonly found in homes throughout the world. With both liquid-based and digital readout thermometers available, the body's temperature can be recorded in several ways. The mouth, the ear and the rectum can all be sources of accurate body heat. For adults, typically the mouth's readings are acceptable. For babies, given their difficulty in remaining still, ear readings are easier to take.