Which of the following are not electromagnetic waves ?

Options

A. `beta`-rays
B. Y -rays
C. x-rays
D. infrared rays

Answer

To determine which of the following options are not electromagnetic waves, we need to refer to the electromagnetic spectrum. The electromagnetic spectrum includes a range of waves such as gamma rays, X-rays, ultraviolet rays, visible light, infrared rays, microwaves, and radio waves.

### Step-by-Step Solution:

1. **Understand the Electromagnetic Spectrum**:
- The electromagnetic spectrum is a continuum of electromagnetic waves arranged according to their frequency or wavelength. It includes gamma rays, X-rays, ultraviolet rays, visible light, infrared rays, microwaves, and radio waves.

2. **List the Given Options**:
- We need to analyze the options provided in the question. For this example, let's assume the options are:
- A) Gamma Rays
- B) X-Rays
- C) Infrared Rays
- D) Beta Rays

3. **Check Each Option Against the Spectrum**:
- **Gamma Rays**: Present in the electromagnetic spectrum.
- **X-Rays**: Present in the electromagnetic spectrum.
- **Infrared Rays**: Present in the electromagnetic spectrum.
- **Beta Rays**: Not present in the electromagnetic spectrum. Beta rays are actually streams of electrons or positrons and are not classified as electromagnetic waves.

4. **Conclusion**:
- After checking all the options against the electromagnetic spectrum, we find that the only option that is not an electromagnetic wave is **Beta Rays**.

### Final Answer:
- The correct answer is **Beta Rays** as they do not exist in the electromagnetic spectrum.