JEE Main 2021
LEVELBoard
Visualized Solution
The Sigma Insight: Thermodynamic Processes
The Four Pillars of Thermodynamics
Decoding the Processes
Thermodynamics is fundamentally the study of energy in motion. To truly understand how heat engines, refrigerators, and even our atmosphere work, we must master the "rules of the road"—the four fundamental thermodynamic processes.
Let's break down the etymology and physics of each process to make matching them completely intuitive.
1
Isothermal: The Temperature Keeper
The word isothermal comes from the Greek roots iso (meaning equal or same) and therme (meaning heat). In an isothermal process, the temperature remains absolutely constant ($
\Delta T = 0
$).
Because the temperature doesn't change, the internal energy of an ideal gas also remains constant. If the gas expands, it must absorb heat from its surroundings to prevent its temperature from dropping. On a diagram, this process follows Boyle's Law (), tracing out a smooth hyperbola.
2
Isochoric: The Rigid Box
Next, we have the isochoric process. The root choric relates to space or volume. Therefore, an isochoric process is one where the volume is constant ($
\Delta V = 0
$).
Imagine heating a gas trapped inside a rigid, sealed steel tank. The gas cannot expand, so it does zero mechanical work (). All the heat you pump into the system goes directly into increasing the internal energy, causing the pressure and temperature to spike. On a diagram, this is represented by a strict vertical line.
3
Adiabatic: The Insulated Vault
The term adiabatic translates to "impassable." In this process, the system is perfectly insulated from its surroundings. No heat enters or leaves the system ($
\Delta Q = 0
$), meaning the heat content is constant.
If an adiabatic gas expands, it must do work at the expense of its own internal energy. As a result, its temperature plummets. Because both the volume increases and the temperature decreases simultaneously, the pressure drops much faster than it would in an isothermal process. This is why the adiabatic curve () is always steeper than the isothermal curve on a diagram.
4
Isobaric: The Open Atmosphere
Finally, we have the isobaric process. The root baric comes from baros, meaning weight or pressure (think of a barometer). In an isobaric process, the pressure remains constant ($
\Delta p = 0
$).
A classic example is boiling water in an open pan. The pressure is locked at 1 atmosphere by the surrounding air, even as the water expands into steam. On a diagram, this process is depicted as a perfectly horizontal line.
The Final Verdict
By understanding the roots of these words, the matching becomes trivial:
- A. Isothermal 2. Temperature constant
- B. Isochoric 3. Volume constant
- C. Adiabatic 4. Heat content is constant
- D. Isobaric 1. Pressure constant
This perfectly aligns with the fourth option, making it the correct choice.
Similar Questions
JEE Main 2020
LEVELJEE Main
Match the thermodynamic processes taking place in a system with the correct conditions. In the table, is heat supplied, is work done and is change in internal energy of the system.
JEE Main 2019
LEVELJEE Main
The given diagram shows four processes, i.e. isochoric, isobaric, isothermal and adiabatic. The correct assignment of the processes, in the same order is given by
(A)
d a b c
(B)
a d b c
(C)
d a c b
(D)
a d c b
JEE Main 2016
LEVELJEE Main
An ideal gas undergoes a quasistatic, reversible process in which its molar heat capacity remains constant. If during this process the relation of pressure and volume is given by , then is given by (Here and are molar specific heat at constant pressure and constant volume, respectively)
(A)
(B)
(C)
(D)
LEVELJEE Main
Starting with the same initial conditions, an ideal gas expands from volume to in three different ways, the work done by the gas is if the process is purely isothermal, if purely isobaric and if purely adiabatic, then
(A)
(B)
(C)
(D)
JEE Advanced 2018
LEVELJEE Main
One mole of a monoatomic ideal gas undergoes a cyclic process as shown in the figure (where, is the volume and is the temperature). Which of the statements below is (are) true ?
* Multiple Correct Options
(A)
Process I is an isochoric process
(B)
In process II, gas absorbs heat
(C)
In process IV, gas releases heat
(D)
Processes I and III are not isobaric
JEE Advanced 2013
LEVELJEE Advanced
One mole of a monatomic ideal gas is taken along two cyclic processes and as shown in the diagram. The processes involved are purely isochoric, isobaric, isothermal or adiabatic. Match the paths in List I with the magnitudes of the work done in List II and select the correct answer using the codes given below the lists. $\begin{array}{clcl} \hline & \text{List I} & & \text{List II} \\ \hline \text{P.} & G \rightarrow E & 1. & 160 p_0 V_0 \ln 2 \\ \text{Q.} & G \rightarrow H & 2. & 36 p_0 V_0 \\ \text{R.} & F \rightarrow H & 3. & 24 p_0 V_0 \\ \text{S.} & F \rightarrow G & 4. & 31 p_0 V_0 \\ \hline \end{array}$
(A)
P-4, Q-3, R-2, S-1
(B)
P-4, Q-3, R-1, S-2
(C)
P-3, Q-1, R-2, S-4
(D)
P-1, Q-3, R-2, S-4
JEE Advanced 2004
LEVELJEE Main
An ideal gas expands isothermally from a volume to and then compressed to original volume adiabatically. Initial pressure is and final pressure is . The total work done is . Then,
(A)
(B)
(C)
(D)
JEE Advanced 2024
LEVELJEE Main
One mole of a monatomic ideal gas undergoes the cyclic process J K L M J, as shown in the P-T diagram. Match the quantities mentioned in List-I with their values in List-II and choose the correct option. [R is the gas constant.]
JEE Advanced 1998
LEVELJEE Main
A given quantity of an ideal gas is at pressure and absolute temperature . The isothermal bulk modulus of the gas is
(A)
(B)
(C)
(D)
JEE Advanced 2003
LEVELJEE Advanced
The - diagram for an ideal gas is shown in the figure, where is an adiabatic process, find the corresponding - diagram
(A)
(B)
(C)
(D)