All degrees are not created equal! It's important to be able to convert between temperatures scales. Steven Taylor / Getty Images The three common temperature scales are Celsius, Fahrenheit, and Kelvin. Each scale has its uses, so it's. The Kelvin scale is an absolute thermodynamic temperature scale using as its null point Unlike the degree Fahrenheit and degree Celsius, the kelvin is not referred to or . Colour temperature is important in the fields of image projection and noisy a circuit is in relation to an ultimate noise floor, i.e. the noise temperature. The Kelvin scale compared to Celsius and Fahrenheit. a theory that examines the relationship between pressure, work and temperature.
Figure InWilliam Thomson, 1st Baron Kelvin, an Irish-Scottish physicistproduced yet another temperature scale that was intended to be more useful than the Fahrenheit or Celsius scales. In Thomson's "absolute" scale, every increase from one degree to the next represented an equivalent amount of energy. The only fixed reference point on the scale was absolute zero, which represented the temperature where no kinetic energy remained in any substance—that is, the temperature where everything was frozen.
This was an abstract concept at that time.
Units of Temperature: from fahrenheit to celsius to kelvin and back
Thomson knew from work by early gas chemists that the volume of a gas at constant pressure was directly proportional to its temperature, and he used this linear relationship to calculate the temperature where pressure would equal zero.
Fahrenheit, Celsius and Kelvin Scales Unlike the Fahrenheit and Celsius scales, the Kelvin scale was developed starting from absolute zero, so it does not have negative values. Today, the Kelvin scale is widely used by scientists, who consider it more useful than other systems because it is based on an absolute value. When a substance's temperature is measured in Kelvins, its value is directly proportional to the average kinetic energy of the molecules of the substance.
And since the Kelvin scale starts at absolute zero, it does not require use of negative numbers, which simplifies calculations.
Figure Glossary Directly proportional Occurs if, as the value of one variable increases, the value of another variable increases at the same rate. Directly proportional Occurs if, as the value of one variable increases, the value of another variable increases at the same rate.
Fahrenheit FCelsius C sometimes called centigradeand Kelvin sometimes called absolute. The relationship between temperatures on these three scales is straightforward if you understand how a thermometer is constructed and calibrated. Two essential features of a thermometer are: In the thermometer with which you may be most familiar, the substance that expands and contracts is mercury. In order to measure its expansion or contraction, the mercury is confined within a small, thin-walled glass bulb connected to a very narrow or capillary tube.
When the temperature increases, the mercury expands and its level in the capillary tube rises. This increase in height is proportional to the increase in temperature.
A thermometer is calibrated in the following manner. First, the mercury bulb of a new thermometer is immersed in a mixture of ice and water. When the height of the mercury in the column remains constant, a mark is made.How to Convert from Kelvin Temperatures to Degrees Celsius
This mark is one reference point. The ice-water mixture is then heated to boiling and kept at that temperature while the height of the mercury in the column rises to a new constant level. Another mark is made on the column at this level; this mark is a second reference point. Further steps depend on whether this thermometer will measure temperature on the Celsius, Fahrenheit, or Kelvin scale.
The distance between these two reference points is divided into equal segments. The distance between these two points is divided into equal segments.
If the thermometer is to measure temperature on the Kelvin scale, the ice-water reference point is labeled Notice that K does not use a degree symbol. The symbol K means "degrees Kelvin.
The relationships between the three temperature scales are illustrated in Figure 2.