The effiency of reversible engine is___the irreversible engine.

Options

A. Less than
B. Greater than
C. Equal to
D. Negligible than

Answer

To solve the question regarding the efficiency of reversible and irreversible engines, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Efficiency**:
Efficiency (\( \eta \)) of an engine is defined as the ratio of the work output to the heat input. It can be expressed mathematically as:
\[ \eta = \frac{W}{Q_h} \]
where \( W \) is the work done by the engine and \( Q_h \) is the heat absorbed from the hot reservoir.

2. **Identify the Types of Engines**:
We have two types of engines to compare: reversible engines and irreversible engines.

3. **Recall Carnot's Theorem**:
According to Carnot's theorem, no engine operating between two heat reservoirs can be more efficient than a reversible engine operating between the same reservoirs. This means:
\[ \eta_{reversible} \geq \eta_{irreversible} \]

4. **Conclusion from Carnot's Theorem**:
Since the reversible engine is the most efficient engine possible, its efficiency will always be greater than that of any irreversible engine operating between the same temperature limits.

5. **Fill in the Blank**:
Based on the understanding from Carnot's theorem, we can conclude that:
\[ \text{The efficiency of a reversible engine is greater than the efficiency of an irreversible engine.} \]

### Final Answer:
The efficiency of a reversible engine is **greater than** the efficiency of an irreversible engine.

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