de-Broglie wavelength applies only to

Options

A. Light particles
B. Electrons
C. Photons
D. All the microscopic matter in motion

Answer

To solve the question regarding the application of de-Broglie wavelength, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding de-Broglie Wavelength**: The de-Broglie wavelength (λ) is given by the formula:
\[ \lambda = \frac{h}{mv} \]
where \(h\) is Planck's constant, \(m\) is the mass of the particle, and \(v\) is its velocity.

2. **Identifying the Context**: The de-Broglie wavelength concept applies to particles that have mass and are in motion. It suggests that all matter exhibits wave-like properties.

3. **Analyzing the Options**:
- **Option A: Light Particle**: Light particles (photons) are massless. The de-Broglie wavelength does not apply to them in the traditional sense since they do not have mass.
- **Option B: Electron**: Electrons are indeed particles with mass, and the de-Broglie wavelength applies to them. However, the question asks for the broader application.
- **Option C: Photon**: Similar to light particles, photons are massless and do not have a de-Broglie wavelength in the classical sense.
- **Option D: All Microscopic Matter in Motion**: This option includes all particles that have mass (like electrons, protons, and neutrons) and are in motion. The de-Broglie wavelength applies to all these particles.

4. **Conclusion**: The correct answer is **Option D: All microscopic matter in motion**. This is because the de-Broglie wavelength applies to any particle with mass that is moving, not just electrons or protons.

### Final Answer:
The de-Broglie wavelength applies only to **all microscopic matter in motion** (Option D).

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