In electromagnetic spectrum, which quantity remains same for all types of wave?

Options

A. speed
B. frequency
C. wavelength
D. none of these

Explanation

To solve the question regarding which quantity remains the same for all types of waves in the electromagnetic spectrum, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Electromagnetic Spectrum**: The electromagnetic spectrum includes various types of waves such as cosmic rays, gamma rays, x-rays, ultraviolet rays, visible light, infrared rays, microwaves, and radio waves. Each type of wave has different properties.

2. **Identify the Key Quantities**: The key quantities we need to consider for electromagnetic waves are:
- Speed
- Frequency
- Wavelength

3. **Analyze the Relationship Between Wavelength, Frequency, and Speed**:
- The speed of electromagnetic waves in a vacuum is constant and is denoted by \( c \), which is approximately \( 3 \times 10^8 \) meters per second.
- The relationship between speed (c), frequency (f), and wavelength (λ) is given by the equation:
\[ c = f \times \lambda \]
- From this equation, we can see that if the speed is constant, any change in frequency will result in a corresponding change in wavelength.

4. **Consider the Variability of Frequency and Wavelength**:
- As we move through the electromagnetic spectrum from left to right (from cosmic rays to radio waves), the wavelength increases while the frequency decreases. This indicates that frequency and wavelength are not constant across the spectrum.

5. **Conclusion**: Since the speed of electromagnetic waves remains constant at \( 3 \times 10^8 \) m/s in a vacuum, while frequency and wavelength vary, the correct answer to the question is:
- **Speed**.

### Final Answer:
The quantity that remains the same for all types of waves in the electromagnetic spectrum is **Speed**.