The working principle of Steam engine is

Options

A. Digital logic
B. Super conductivity
C. Laws of thermodynamics
D. Nuclear fission

Answer

### Step-by-Step Solution:

1. **Understanding the Steam Engine**: A steam engine is a type of heat engine that converts thermal energy (heat) into mechanical energy (work).

2. **Heat to Mechanical Work Conversion**: The steam engine operates by using heat energy to produce steam, which then expands and pushes a piston. This expansion of steam is what creates the mechanical work.

3. **First Law of Thermodynamics**: The working principle of the steam engine can be explained using the first law of thermodynamics, which states that the change in internal energy (ΔU) of a system is equal to the heat added to the system (Q) minus the work done by the system (W). Mathematically, it is expressed as:
\[ ΔU = Q - W \]
In the case of a steam engine, the heat supplied is converted into work done by the engine.

4. **Piston Movement**: Inside the steam engine, when heat is supplied to the water, it converts into steam. The high-pressure steam pushes the piston, causing it to move back and forth. This motion is harnessed to perform mechanical work, such as turning wheels or driving machinery.

5. **Conclusion**: Therefore, the working principle of a steam engine is based on the conversion of heat energy into mechanical work through the expansion of steam, following the laws of thermodynamics.