What units are used to measure temperatures?

Answer 1

There are various scales used to measure temperature:

• Celsius (Centigrade)

It uses the symbol °C - degrees Celsius

This is based on the freezing point of water at 0°C and boiling point at 100 °C. When Anders Celsius devised his scale he set the freezing point at 100° and boiling point at 0°; the sale was inverted by another scientist shortly after his death.

It was known as centigrade as it uses 100 degrees between its defining points, but is now known in honour of the Swedish scientist Anders Celsius.

• Fahrenheit

It uses the symbol °F - degrees Fahrenheit

It was based on the freezing point of brine at 0°F, the freezing point of water at 32°F and body temperature at 96°F. By using these points it was easy to mark the scale by bisecting between points (between 96°F and 32°F is 64°F which is easy to bisect into degree marks).

Due to slight inaccuracies in the original construction, the scale was slightly wrong and is now based on freezing point of water at 32°F and boiling point at 212°F (to match 0°C and 100°C).

• Kelvin

It uses the symbol K - Kelvin (it has no degrees)

It is based on absolute zero; there can be no negative Kelvin temperatures. Is uses the same scale as Celsius - it is the Celsius scale shifted so that 0K = absolute zero = -273.15°C, freezing point of water = 273.15K = 0°C

Kelvin is the SI unit of temperature.

There are further scales which are used less often (or not at all):

• Rankine

It uses the symbol °Ra - degrees Rankine. It can also use °R or just R.

Like the Kelvin scale it is based on absolute zero, but it uses the same scale as Fahrenheit - it is the Fahrenheit scale shifted so that 0°Ra = absolute zero = -459.67°F, freezing point of water = 491.67°Ra = 32°F

• Delisle

It uses the symbol °D - degrees Delisle

It was based on the boiling point of water at 0°D and then marked with graduations as the temperature fell. It was later recalibrated to keep boiling water at 0°D and the freezing point of water at 150°D.

• Rømer

It uses the symbol °Rø - degrees Rømer. It can also use °R.

It was based on the freezing point of brine at 0°Rø and the boiling point of water at 60°Rø; this made the freezing point of water about 7.5°Rø, so the scale was re-based on freezing point of water at 7.5°Rø and boiling point at 60°Rø.

• Réaumur

It uses the symbol °Ré (Degrees Réaumur). It can also use °Re or °r.

It was based on the freezing point of water at 0°Ré and boiling point at 80°Ré.

• Newton

It uses the symbol °N (degrees Newton)

It was based on the temperature of melting snow at 0°N, but no other point was used. Newton was working at the Royal Mint and was interested in the melting of metals. He noted that water boiled at

33°N.

It is possible to convert between the scales (based on freezing and boiling points of water); for the Newton scale, due to its inception, only a rough conversion is possible.

Answer 2

Two common units to measure temperature are Fahrenheit and Celsius.

Answer 3

Kelvin, Fahrenheit and Celsius.

Answer 4

100 degrees