Temperature and Heat

Every day, heat and temperature are vital ideas for each of us. The way we dress in the morning is determined by whether the day is hot or cold, and the majority of what we accomplish takes energy from the Sun. Thermodynamics is a branch of physics that deals with heat and temperature. 

The movement of energy throughout the universe is governed by thermodynamic rules. From chemistry to biology to environmental science, they are researched in many fields of science and engineering.

Heat and temperature are usually correlated to each other. When you heat a substance, one of two things can happen: the temperature will rise, or the condition of the substance will change.

Let us understand the concept of heat and temperature:

Concept of heat and temperature

Temperature – The amount measured by a thermometer is operationally defined as temperature. It’s proportional to the average kinetic energy of the system’s atoms and molecules. When two bodies are in contact and can easily exchange energy, thermal equilibrium occurs. When two systems have the same temperature, they are in thermal equilibrium. 

Heat – Heat is a sort of energy transmission that occurs when a temperature differential exists and can cause an object’s temperature to vary. Heat transfer is the passage of energy from one place or material to another as a result of a temperature differential, as we learned previously in this chapter. Many industrial processes, as well as ordinary activities like house heating and cooking, rely on heat transfer.

Heat is a sort of energy transmission that occurs when a temperature differential exists and can cause an object’s temperature to vary. Heat transfer is the passage of energy from one place or material to another as a result of a temperature differential, as we learned previously in this chapter. Many industrial processes, as well as ordinary activities like house heating and cooking, rely on heat transfer.

Measurement of heat and temperature

Temperature measurement 

A substance’s temperature can be determined based on its various features:

Liquid thermometer – A narrow tube with an attached scale, a liquid—usually mercury or colored alcohol—is placed. The volume variations in the liquid as it heats or cools are used to determine the temperature. The thermometer’s liquid must be able to:

• Over a wide temperature range, they expand swiftly and uniformly
• not adhere to the tube’s walls

Water is not suitable because of its unusual expansion, i.e., if heated from -15°C, it expands only till 0°C. It begins to melt and compress at this stage, reaching a temperature of 4 degrees Celsius. The water expands consistently until it reaches the boiling point when heated further. A substance’s temperature can be determined based on a variety of factors.

Gas thermometer – Similar to a liquid thermometer, a drop of mercury is inserted into a narrow tube. The tube contains a little amount of gas, which expands when heated and contracts when cooled.

Bimetallic thermometer -The thermal expansion of a substance varies based on its composition. A coiled bimetallic strip, which is attached to an indicator, is made up of two different types of metal. When the bimetallic strip is heated, the two metals expand at opposite rates, causing the indicator to bend.

Electronic/Resistance thermometer – Temperature has a big influence on electric resistance, especially in semiconductors. A thermistor’s resistance reduces as the temperature rises. A decrease in resistance causes an increase in current flow, which causes the temperature to change.

Heat measurement 

The amount of heat absorbed by a material is proportional to its mass and temperature change. The specific heat capacity is the amount of heat required to heat one kilogram of a certain substance by one degree Celsius. The specific heat capacity, which is the change in heat within a body and hence the change in interior kinetic energy, can be measured with a calorimeter such as a heat flow calorimeter, a heat balance calorimeter, or an adiabatic calorimeter.

The following formula is used to calculate heat:

ΔQ = c * m * ΔT

The product of a body’s specific heat capacity (c), mass (m), and temperature(T) change equal to the heat(Q) received or emitted by that body.

There are three methods in which heat can be transferred:

Conduction – Heat transmission between molecules in direct touch with each other without the movement of particles is known as conduction.

Convection – It is the heat transfer that occurs as a result of the movement of particles from one location to another.

Radiation – It occurs when heat is transported via material or vacuum with no heating of the area in between.

Thermal convection

Conduction, convection, and radiation are the three methods through which heat can be transmitted. Heat is transmitted from a hotter body to a cooler one in this procedure.

When a body is heated in one location, the density of the liquid at that location decreases as the temperature rises. Buoyancy causes the warm liquid to rise and the colder liquid to sink, resulting in the movement of water mass carrying heat energy.

Conclusion

The thermodynamics concepts of heat and temperature work together to allow energy to flow from a hotter body to a cooler body. While heat is dependent on the number of particles in an object, the temperature is independent of the number of particles because it is an average measurement.