The adjective macroscopic implies that we can observe these properties and phenomena without the need for a microscope.
Temperature
This refers to the average kinetic energies (translational, rotational and vibrational) of the particles within an object or system. It is how hot or cold something is. Absolute temperature is measured in $Kelvin\ (K)$. Other units used for temperature are:
- Degree Celsius ($\degree C$) aka degree centigrade
- Degree Farenheit ($\degree F$)
Direction of heat flow
Heat energy moves from hot to cold (from regions of higher temperature to regions of lower temperature). In other words, heat flows along the temperature gradient not against it.
Thermometric properties
These are properties of an object/system which change in value based on the temperature of the object/system.
- A common example is the volume of the mercury trapped in a mercury thermometer
- The cross sectional area of the tube can be considered as constant so changes in volume are seen as changes in length of the mercury
- Other examples include electrical resistance, length, pressure and volume
Measuring temperature
There are many devices which are used to measure temperature. Examples include laboratory thermometers, clinical thermometers and thermocouples.
The Celsius Scale
The Celsius scale also known as the centigrade scale is defined relative to two points:
- The Lower Fixed Point – the freezing point of water ($0\degree C$)
- The Upper Fixed Point – the boiling point of water ($100\degree C$)
The interval between these two fixed points is divided up into 100 parts (hence why it is called the centigrade scale.
- A temperature difference of $1\degree C$ is the same as that of $1\ K$
- The Celsius and Kelvin scales are only different in that they designate ‘zero’ as different points
- The Celsius scale’s zero is at $273\ K(0\degree C)$ and the Kelvin scale’s zero (normally referred to as absolute zero) is $-273\degree C(0\ K)$
Credits: University of Central Florida