LABORATORY THERMOMETER (-10°C - 110°C)

Product Information

The model comes with a 9V battery already installed, cleaning instructions, and a five-year limited product warranty. Apart from the absolute zero of temperature, the Kelvin temperature of a body in a state of internal thermodynamic equilibrium is defined by measurements of suitably chosen of its physical properties, such as have precisely known theoretical explanations in terms of the Boltzmann constant. [ citation needed] That constant refers to chosen kinds of motion of microscopic particles in the constitution of the body. In those kinds of motion, the particles move individually, without mutual interaction. Such motions are typically interrupted by inter-particle collisions, but for temperature measurement, the motions are chosen so that, between collisions, the non-interactive segments of their trajectories are known to be accessible to accurate measurement. For this purpose, interparticle potential energy is disregarded.

A thermometer is calibrated by using two objects of known temperatures. The typical process involves using the freezing point and the boiling point of pure water. Water is known to freeze at 0°C and to boil at 100°C at an atmospheric pressure of 1 atm. By placing a thermometer in mixture of ice water and allowing the thermometer liquid to reach a stable height, the 0-degree mark can be placed upon the thermometer. Similarly, by placing the thermometer in boiling water (at 1 atm of pressure) and allowing the liquid level to reach a stable height, the 100-degree mark can be placed upon the thermometer. With these two markings placed upon the thermometer, 100 equally spaced divisions can be placed between them to represent the 1-degree marks. Since there is a linear relationship between the temperature and the height of the liquid, the divisions between 0 degree and 100 degree can be equally spaced. With a calibrated thermometer, accurate measurements can be made of the temperature of any object within the temperature range for which it has been calibrated. A bulb one end contains most of the mercury. The contraction and expansion of this quantity is amplified within the capillary tube. The void is usually either a vacuum or filled with nitrogen.

Questions & Answers

Thermodynamic temperature" is distinct from temperatures based on freezing and melting points of fluids, Julia Scherschligt, an expert in vacuum and pressure metrology at the National Institute of Science and Technology in the United States, told Live Science. The iHealth No-Touch Forehead Thermometer PT3 reads in just one second and makes it easy to accurately take anyone's temperature while being socially distant.

Photo: A typical thermometer consists of a liquid in a tube that rises and falls against a linear scale

For an accurate reading, the ear thermometer must be inserted into your baby’s ear canal. To reach the ear canal, parents frequently have to tug their newborns’ ears and tilt their small heads, a process that most babies find distressing, and which can affect the accuracy of the reading if they wiggle around. When tested repeatedly, the Exergen thermometer delivered the most consistent and precise results of any model tested on myself and my kids — within 0.3 degrees.

Traditionally slow to adopt the metric system and other accepted units of measurements, the United States more commonly uses the Fahrenheit temperature scale. A thermometer can be calibrated using the Fahrenheit scale in a similar manner as was described above. The difference is that the normal freezing point of water is designated as 32 degrees and the normal boiling point of water is designated as 212 degrees in the Fahrenheit scale. As such, there are 180 divisions or intervals between these two temperatures when using the Fahrenheit scale. The Fahrenheit scale is named in honor of German physicist Daniel Fahrenheit. A temperature of 76 degree Fahrenheit is abbreviated as 76°F. In most countries throughout the world, the Fahrenheit scale has been replaced by the use of the Celsius scale. After Fahrenheit's death in 1736, the Fahrenheit scale was recalibrated to make it slightly more accurate. The exact freezing and boiling points of plain water, minus the salt, were marked at 32 and 212 degrees Fahrenheit, respectively. Normal human body temperature was marked at 98.6.While the Celsius and Fahrenheit scales are the most widely used temperature scales, there are several other scales that have been used throughout history. For example, there is the Rankine scale, the Newton scale and the Romer scale, all of which are rarely used. Finally, there is the Kelvin temperature scale, which is the standard metric system of temperature measurement and perhaps the most widely used temperature scale among scientists. The Kelvin temperature scale is similar to the Celsius temperature scale in the sense that there are 100 equal degree increments between the normal freezing point and the normal boiling point of water. However, the zero-degree mark on the Kelvin temperature scale is 273.15 units cooler than it is on the Celsius scale. So a temperature of 0 Kelvin is equivalent to a temperature of -273.15 °C. Observe that the degree symbol is not used with this system. So a temperature of 300 units above 0 Kelvin is referred to as 300 Kelvin and not 300 degree Kelvin; such a temperature is abbreviated as 300 K. Conversions between Celsius temperatures and Kelvin temperatures (and vice versa) can be performed using one of the two equations below. Today, there are a variety of types of thermometers. The type that most of us are familiar with from science class is the type that consists of a liquid encased in a narrow glass column. Older thermometers of this type used liquid mercury. In response to our understanding of the health concerns associated with mercury exposure, these types of thermometers usually use some type of liquid alcohol. These liquid thermometers are based on the principal of thermal expansion. When a substance gets hotter, it expands to a greater volume. Nearly all substances exhibit this behavior of thermal expansion. It is the basis of the design and operation of thermometers.

Empirically based temperature scales rely directly on measurements of simple macroscopic physical properties of materials. For example, the length of a column of mercury, confined in a glass-walled capillary tube, is dependent largely on temperature and is the basis of the very useful mercury-in-glass thermometer. Such scales are valid only within convenient ranges of temperature. For example, above the boiling point of mercury, a mercury-in-glass thermometer is impracticable. Most materials expand with temperature increase, but some materials, such as water, contract with temperature increase over some specific range, and then they are hardly useful as thermometric materials. A material is of no use as a thermometer near one of its phase-change temperatures, for example, its boiling-point. Experimental physicists, for example Galileo and Newton, [53] found that there are indefinitely many empirical temperature scales. Nevertheless, the zeroth law of thermodynamics says that they all measure the same quality. This means that for a body in its own state of internal thermodynamic equilibrium, every correctly calibrated thermometer, of whatever kind, that measures the temperature of the body, records one and the same temperature. For a body that is not in its own state of internal thermodynamic equilibrium, different thermometers can record different temperatures, depending respectively on the mechanisms of operation of the thermometers.perfectly safe if it's sealed inside a thermometer. However, if the glass tube of a mercury thermometer Precise electrical thermometers, known as resistance thermometers, use four resistors arranged in a diamond-shaped circuit called a Wheatstone bridge. If three of the resistors have known values, the resistance of the fourth Make sure to keep your thermometer away from direct heat sources or sunlight as this will affect its accuracy. The magnitude of the kelvin is now defined in terms of kinetic theory, derived from the value of the Boltzmann constant. When you hear weather forecasts give Celsius temperatures and their Fahrenheit equivalents, you might feel the relationship between them is a little bit odd and confusing, because they seem so different. But if you plot them on a chart (as I have below), you can see that both scales are perfectly linear, and every rise of temperature that adds another 10°C adds 18°F.