Imagine a world without the knowledge of temperature—no forecasts warning us about a scorching day or a bone-chilling evening, no perfectly cooked steak, or safely preserved vaccines. That’s where thermometry makes its grand entrance.
Temperature measurement isn’t just a fancy trick up a scientist’s sleeve; it’s crucial for everyday life. Ensuring your steak is grilled to succulent perfection, gauging whether it’s a light sweater or a heavy coat kind of day—thermometry is there, quietly underpinning our daily decisions.
But what exactly is thermometry?
Thermometers are instruments or devices used for measuring the temperature of objects or the environment. They function by perceiving and recording physical quantities or characteristics related to temperature, which are then converted into numerical, pointer, or other forms of readings to provide a quantitative measurement of temperature.
The basic principle of a thermometer is to utilize the measurable response or effect produced by a substance when its temperature changes. These effects can include changes in volume, electrical resistance, electromotive force, radiation intensity, and more. Based on different principles and mechanisms of operation, thermometers may employ a variety of sensors and measurement methods.
Thermometers are extensively used across various fields, including industrial control, medical diagnostics, meteorological forecasting, and scientific research. They help us understand and monitor temperature changes, thus facilitating process control, disease diagnosis, weather analysis, and scientific experiments. The accuracy, precision, and speed of temperature measurement of thermometers are crucial for many applications and play a significant role in numerous industries and sectors.
Principles of Thermometers
The principles and operating methods of thermometers vary according to their type. Here are some common types of thermometers and their corresponding principles and modes of operation:
Based on the thermal expansion and contraction properties of liquids. Mercury expands and moves up with an increase in temperature, and contracts and moves down with a decrease in temperature. The scale of the thermometer is calibrated according to the changes in the height of the mercury column to determine temperature.
Utilize the relationship between resistance and temperature. Common thermistor materials such as platinum, nickel, and copper change their resistance value with temperature fluctuations, allowing temperature to be determined by measuring the resistance.
Thermocouples consist of two wires made from different metals that are joined at one end. This junction forms the sensing point. Based on the thermoelectric effect between two different metals. When there is a temperature difference between the two junctions of the thermocouple, an electromotive force (voltage) is generated. Temperature is determined by measuring this voltage difference.
A notable feature of thermocouple thermometers is their rapid temperature measurement capability. Thermocouples are simpler and tinier than thermistors because they don’t need extra stuff like carbon and a coating. This design lets them be placed at the very tip of a probe, which helps it measure temperature changes super quickly.
A prominent example of such thermometers on the market is the Typhur InstaProbe Thermocouple Thermometer, which boasts a reading speed of 0.5 seconds.
Use the infrared radiation emitted by an object to measure its surface temperature. Infrared thermometers employ optical components and detectors to convert infrared radiation into an electrical signal, and algorithms then translate this signal into a temperature reading.
Thermal Imagers/Infrared Thermal Cameras
Generate thermal images by detecting and recording the distribution of infrared radiation intensity from the surface of the target object. The temperature distribution on the object’s surface can be determined based on the radiation intensity of different areas.
These are the common types of thermometers with their principles and modes of operation. Each type of thermometer has its advantages and scope of application. The choice of the appropriate thermometer depends on practical needs, measurement range, and precision requirements, among other factors.