Grade 7 | Science | Heat and temperature, Heat, Olympiad, CBSE, ICSE, SOF, ITO
What is heat?
Heat being a form of energy causes us to feel hot and cold and it always flows from hot objects to cold objects.
We wear woolen clothes during winters when it is cold outside as woolen clothes keep us warm by trapping the heat inside. During summers we eat ice cream to get relieved from the hot summer days. How do we know about this hot and cold concept? It is understood by the sensation formed by the heat in our body when the temperature outside changes the body changes.
What is Temperature?
It is the degree of hotness and coldness of a body. Temperature can be determined by checking the flow of heat as it always flows from a body with a higher temperature to the body a body of lower temperature. The transfer of heat keeps going on between the two bodies until they reach a state of equilibrium where the temperature of two bodies become the same.
We can also infer from the above information that heat is a cause while the temperature is an effect.
The S.I unit of heat is joule (j). But conventionally heat is measured in calories (Cal). The amount of heat energy required to raise the temperature of 1 g of water by 1°C is called 1 calorie.
Scales to measure the temperature
We use a thermometer to measure the temperature and there are three different scales for this.
1. Celsius scale
2. Fahrenheit scale
3. Kelvin scale
1. Celsius scale- It has 100 divisions and each division measure s one degrees Celsius (°C). Here, in this scale, the lowest freezing point is marked as 0°C stating the freezing point of water and the highest limit is marked at 100°C which is the boiling point of water
2. Fahrenheit scale- It has 180 divisions and each of which measures 1°F. It shows the melting point of ice at 32° F and shows steam point marked at 213°F.
3. Kelvin scale- It is known as an absolute scale of temperature and was introduced by Lord Kelvin. In this scale the lowest limit of temperature is zero. Here zero means it is equally to -212°C.