Question:medium

For given four processes compare magnitude of work:

Updated On: Apr 8, 2026
  • \( |W_1|>|W_2|>|W_3|>|W_4| \)
  • \( |W_1|<|W_2|<|W_3|<|W_4| \)
  • \( |W_1|<|W_3|<|W_2|<|W_4| \)
  • \( |W_2|<|W_1|<|W_4|<|W_3| \)
Show Solution

The Correct Option is D

Solution and Explanation

Step 1: Understanding the Question: 
The goal is to compare the magnitude of work done in irreversible isothermal expansion and compression processes involving single and multiple steps. 
Step 2: Key Formula or Approach: 
1. Work is the area under the P-V curve. 
2. For expansion: \(|W_{\text{reversible}}|>|W_{\text{multistep}}|>|W_{\text{single-step}}|\). 
3. For compression: \(|W_{\text{single-step}}|>|W_{\text{multistep}}|>|W_{\text{reversible}}|\). 
Step 3: Detailed Explanation: 

- In expansion, the system does work against an external pressure. A multi-step expansion (I) stays closer to the isotherm, covering more area under the curve than a single-step expansion (II), where the system immediately works against the lower final pressure. Hence, \(|W_1|>|W_2|\). 
- In compression, work is done on the system. In a single-step compression (III), you immediately apply the maximum final pressure, resulting in the largest possible area. In multi-step compression (IV), you increase pressure gradually, reducing the "excess" work required. Hence, \(|W_3|>|W_4|\). 
- Comparing expansion vs compression between the same volume limits: the compression work (work done on the gas) is always greater than the expansion work (work done by the gas). 
Therefore, the combined order of magnitudes is: \(|W_2|<|W_1|<|W_4|<|W_3|\). 
Step 4: Final Answer: 
The correct magnitude order is \(|W_2|<|W_1|<|W_4|<|W_3|\). 
 

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