The speed of electromagnetic wave is same for

Options

A. odd frequencies
B. even frequencies
C. all frequencies
D. all intensities

Explanation

To solve the question "The speed of electromagnetic wave is same for?", we need to analyze the factors that affect the speed of electromagnetic waves.

### Step-by-Step Solution:

1. **Understanding Electromagnetic Waves:**
Electromagnetic waves (EM waves) travel at a speed denoted by 'c' in a vacuum, which is approximately \(3 \times 10^8\) m/s. This speed can change when EM waves travel through different media.

2. **Factors Affecting Speed:**
The speed of electromagnetic waves is influenced by the medium through which they travel. In a vacuum, all EM waves travel at the same speed. However, when they pass through a medium, their speed can vary based on the medium's refractive index.

3. **Frequency and Wavelength Relationship:**
The speed of an electromagnetic wave is related to its frequency (f) and wavelength (λ) by the equation:
\[ c = f \cdot \lambda \]
If the frequency changes, the wavelength must also change to keep the speed constant in a vacuum. However, in a medium, different frequencies can result in different speeds due to varying refractive indices.

4. **Considering Different Frequencies:**
- Odd frequencies and even frequencies: The speed of EM waves can differ for different frequencies when traveling through a medium. Thus, the speed is not the same for odd and even frequencies.
- All frequencies: Since different frequencies can result in different wavelengths and thus different speeds in a medium, the speed is not the same for all frequencies.

5. **Considering Different Intensities:**
The intensity of light refers to the amount of energy it carries per unit area. However, the speed of light does not depend on intensity. Regardless of how much light (intensity) is present, the speed remains constant in a given medium.

6. **Conclusion:**
Therefore, the speed of electromagnetic waves is the same for all intensities but can vary for different frequencies when traveling through a medium.

### Final Answer:
The speed of electromagnetic wave is the same for all intensities.