30 Mar Science Tuition – Temperature
In this Science tuition lesson, we will be finding out more about temperature.
Temperature measures how hot or cold a body is with respect to a standard object. There are two basic concepts which talks about temperature changes are thermal contact and thermal equilibrium. When two objects are in thermal contact, they can affect each other’s temperature. Thermal equilibrium exists when two objects in thermal contact no longer affect each other’s temperature. For example, if a carton of milk from the refrigerator is set on the table, the two objects are in thermal contact. After several hours, their temperatures are the same, and they will be in thermal equilibrium.
Temperature is measured with a thermometer. The basic operating principle behind all thermometers is that there is some quantity which is called a thermometric variable, which changes in response to changes in temperature. The relationship between temperature and the thermometric variable may be direct or inverse proportional. It is the thermometric variable that gets measured and not the temperature. Temperatures are commonly measured in the Kelvin (K) or Celsius scales (°C).
There are different types of thermometer to measures the different thermometric variables. For example, liquid in glass measures volume, constant volume gas measures pressure, bimetallic strip measures coil pitch, electric resistor measures resistance while thermocouple measures voltage.
Liquid in glass thermometers, which consist of a glass reservoir of liquid attached to a narrow glass tube. When the temperature increases, the liquid expands and rises up the tube. When the temperature decreases, the liquid contracts and falls back down the tube. The height of the column is directly related to the temperature in a simple linear fashion.
A fun fact in which the first thermometer was constructed in what is now northern Italy in the Seventeenth Century by Sanctorius Sanctorius (1561–1636).