Question

• Explain in details the P-V and T-V diagrams (thermodynamcis)

I need their explannation and their clear meaning

if it is hand-written, keep it clear please

Answer 1

P-V is Pressure-Volume and T-V is Temperature-Volume diagram. Any point on any graph (diagram) shows the state and that state shows various properties. Curve on the graph shows path of process (Change of state). So Any point on P-V and T-V diagram (or any other diagram) represents the state of the system means at any point this much pressure, volume and temperature contains.

Lets understand about P-V diagram with piston cylinder example. When piston compresses, Its volume decreases and pressure increases. (from basic understanding or PV = nRT). So when piston is at starting position (beginning to compress gas) , The gas in cylinder will have specific pressure, Volume and Temperature (Basic values). So you plot in P-V diagram that value of pressure and volume as point, which shows the initial state of piston. Now piston begins to compress so Value of pressure, Volume and Temperature varies and you reach the end position of piston. At the end state, That gas will have certain value. Plot that value as point on diagram and the process of compression shown by various curve. Lets assume the process of compression was adiabatic, then the curve will look like as shown in picture below. (P-V, T-V diagram will look same in this case) There are different processes mainly isochoric, isothermal, isobaric, adiabatic, polytropic. I am assuming you just started studying this subject so you may not know this. so do not panic.

It is not necessary that all properties (P,V,T) will change during process. In some process, only temperature and volume changes but not pressure. Lets see this example. Take one closed beaker filled with gas and heat that on stove or anything. When you started heating, Properties of gas will change. (See below figure to understand more clearly) After some time when pressure of gas will be equal to the atmospheric pressure, only temperature and volume will change.