Measuring temperature and temperature scales
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Explainer Video
Summary
Measuring temperature and temperature scales
In a nutshell
Temperature is a measure of hotness. If an object is hotter than another there is a net flow of thermal energy from hot to cold until thermal equilibrium is reached. Temperature can be measured with degrees Celsius on the Celsius scale or with kelvin on the absolute temperature scale.
Definitions
Key Words | Definition |
| Temperature | Temperature is a measure of hotness on a chosen scale. |
| Thermal equilibrium | Thermal equilibrium is the point at which there is no net thermal energy flow between two objects as they have the same temperature. |
Equations
description | equation |
| Celsius to kelvin conversion | |
Variable definitions
quantity name | symbol | derived units | alternative units | si base units |
| | | | | |
Temperature
Temperature is a measure of hotness on a chosen scale. If two objects are in contact with each other and one has a higher temperature, there will be a net flow of thermal energy from the hotter object to the colder one.
1. | Block A is hotter than block B |
2. | When the blocks are in contact, heat flows from A to B |
3. | The blocks reach thermal equilibrium |
The thermal energy will flow until the objects reach thermal equilibrium. This is the point at which there is no net energy flow between them as they have the same temperature.
Temperature scales
There are different scales that measure temperature, the most popular being the Celsius scale with units . A temperature scale needs two fixed points at defined temperatures, for the Celsius scale these are the freezing point of water at and the boiling point of water at with 100 increments in between them.
Another scale is the absolute temperature scale with the SI base unit kelvin . The increments on this scale are the same as on the Celsius scale but they go down to absolute zero (), the lowest possible temperature. The freezing point of water is at which means that to convert between the two scales you can use the approximation:
Example
Convert into kelvin.
Firstly, write down the temperature:
Next, write down the conversion between Celsius and kelvin:
Now substitute the number and calculate the temperature in kelvin:
is equivalent to .
FAQs - Frequently Asked Questions
What is temperature?
Temperature is a measure of hotness on a chosen scale.
What is thermal equilibrium?
Thermal equilibrium is the point at which there is no net thermal energy flow between two objects as they have the same temperature.
What is the SI unit for temperature?
The SI unit for temperature is the kelvin K.