smoke precipitator work on the principal of :

Options

A. mass
B. energy
C. momentum
D. velocity

Explanation

To determine the principle on which a smoke precipitator works, let's analyze the options provided:

1. **Mass**
2. **Energy**
3. **Momentum**
4. **Velocity**

### Step-by-Step Solution:

**Step 1: Understanding Smoke Precipitators**
A smoke precipitator is a device used to remove particles from a gas, typically in industrial applications to clean emissions. It works by applying an electric charge to the particles in the smoke.

**Hint 1:** Think about how smoke precipitators interact with particles in the air.

**Step 2: Analyzing the Options**
- **Mass**: While mass is a fundamental property of matter, it does not directly explain how a smoke precipitator functions.
- **Energy**: Energy is involved in many processes, but it does not specifically relate to the mechanism of particle removal in smoke precipitators.
- **Momentum**: Momentum involves mass and velocity, but it is not the primary principle behind how smoke precipitators operate.
- **Velocity**: Velocity refers to the speed of an object in a particular direction. However, it does not directly explain the functioning of a smoke precipitator.

**Hint 2:** Consider the role of electric charges in the operation of smoke precipitators.

**Step 3: Identifying the Correct Principle**
Smoke precipitators primarily work on the principle of **electrostatic attraction**. When the particles in the smoke are charged, they are attracted to oppositely charged plates, which leads to their removal from the gas stream.

**Hint 3:** Focus on how the electric charge affects the particles in the smoke.

**Step 4: Conclusion**
Given the options provided, none of them directly correspond to the principle of electrostatic attraction. However, if we must choose from the given options, **momentum** (C) could be the closest, as it relates to the movement and behavior of particles, but it is important to note that the actual working principle is based on electrostatics.

**Final Answer:** The smoke precipitator works primarily on the principle of electrostatic attraction, but from the provided options, the closest answer is **C. Momentum**.