Question
(a) What is an isochoric process? What is its equation of state? Plot P versus V graph.
(b) Discuss the isochoric process using first law of thermodynamics.
(c) What is the work done by or on the gas in isochoric process?
Solution
(a) Isochoric process is the process in which volume of gas remains constant.
i.e., ∆V = 0.
An ideal gas equation is given by,
In an isochoric process, V is constant.
Therefore the equation of state for isochoric process reduces to,
P versus V graph is as shown below:
(b) According to first law of thermodynamics,
Here,
Therefore
So, the quantity of heat absorbed or rejected is equal to increase or decrease in energy respectively.
(c) The volume of gas is constant in the isochoric process.
Therefore, the work done by or on the gas is zero.
i.e., ∆V = 0.
An ideal gas equation is given by,
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In an isochoric process, V is constant.
Therefore the equation of state for isochoric process reduces to,

P versus V graph is as shown below:

(b) According to first law of thermodynamics,

Here,

Therefore

So, the quantity of heat absorbed or rejected is equal to increase or decrease in energy respectively.
(c) The volume of gas is constant in the isochoric process.
Therefore, the work done by or on the gas is zero.