Which of the following are not electromagnetic waves?

Options

A. Cosmic rays
B. Gamma rays
C. `beta-`rays
D. X - rays

Explanation

To determine which of the following are not electromagnetic waves, we can analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Electromagnetic Waves**: Electromagnetic waves are waves that propagate through space and consist of oscillating electric and magnetic fields. They include gamma rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves.

2. **Identifying the Options**: We need to identify the options given in the question. The common options that might be included are:
- Gamma rays
- X-rays
- Beta rays
- Cosmic rays

3. **Analyzing Each Option**:
- **Gamma Rays**: These are high-energy electromagnetic waves. Therefore, gamma rays are electromagnetic waves.
- **X-rays**: Similar to gamma rays, X-rays are also a form of electromagnetic radiation. Thus, X-rays are electromagnetic waves.
- **Beta Rays**: Beta rays are streams of electrons or positrons emitted by certain types of radioactive nuclei. Since they are charged particles and not waves, beta rays are not electromagnetic waves.
- **Cosmic Rays**: Cosmic rays are high-energy particles from outer space, primarily protons and atomic nuclei. They are not electromagnetic waves but rather particles.

4. **Conclusion**: From the analysis, we can conclude that the options that are not electromagnetic waves are:
- Beta rays
- Cosmic rays

### Final Answer:
The options that are not electromagnetic waves are **Beta rays and Cosmic rays**.

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