Isochoric - Of equal or constant volume, usually applied to a thermodynamic process during which the volume of the system remains

unchanged.

 

For an isochoric process: all the heat being transferred to the system is added to the system's internal energy. If the quantity of gas stays

constant, then this increase in energy is proportional to an increase in temperature.

 

On a P-V diagram, an isochoric process appears as a straight vertical line.

 

Because there is no area under such a line, or in other words no work is done, by or on, the thermodynamic system in an isochoric process. The first law of thermodynamics thus implies that the change in internal energy exactly matches the heat flow:

 

Isobaric (Constant Pressure)

Isochoric (Constant Volume)

Isothermal (Constant Temperature)