What are the differences between a thermometer and a temperature gun?

    Under normal circumstances, thermometers and infrared thermometers differ in terms of principles, measurement sites, accuracy, usage scenarios, and measurement duration. The detailed analysis is as follows:

    1. Different Principles

    Thermometers, such as mercury thermometers, operate based on the principle of thermal expansion and contraction. When heated, the mercury expands in volume and rises along the narrow glass tube inside the thermometer. The body temperature value can then be read according to the scale corresponding to the mercury column. Infrared thermometers measure body temperature by capturing the infrared radiation emitted from the human body, then applying black body radiation theory to convert the infrared energy into a corresponding temperature value.

    2. Measurement Sites

    Thermometers can be used to measure body temperature at various sites such as the armpit, oral cavity, and rectum. For example, during armpit measurement, the mercury end of the thermometer should be placed deep in the armpit and held tightly. Infrared thermometers are primarily used to measure forehead temperature. During use, aim the thermometer at a suitable distance above the midpoint of the eyebrows and press the measurement button to quickly obtain the temperature reading. Some models can also measure wrist temperature, although this is relatively less common.

    3. Accuracy

    Thermometers generally offer higher accuracy; as long as they are used correctly and placed properly, their readings are relatively less affected by external factors. In contrast, the accuracy of infrared thermometers is relatively lower and can be easily influenced by ambient temperature, whether the subject's forehead is sweaty, hair obstruction, and measurement distance.

    4. Usage Scenarios

    Thermometers are suitable for situations requiring precise temperature measurement, such as medical diagnosis and home health monitoring. Infrared thermometers are ideal for rapid initial temperature screening in settings like airports, train stations, schools, and kindergartens where large numbers of people pass through.

    5. Measurement Duration

    Thermometers, such as mercury thermometers, typically require 5-10 minutes for armpit measurements, around 3-5 minutes for oral measurements, and approximately 3 minutes for rectal measurements, which is slightly shorter. Infrared thermometers provide extremely fast measurements; pressing the measurement button usually results in a temperature reading within a few seconds.

    Before using a thermometer, ensure that the contact area of the thermometer is clean and free of debris to avoid affecting the measurement results.