Red light differs from blue light in its

Options

A. speed.
B. frequency
C. intensity
D. amplitude

Answer

To answer the question about how red light differs from blue light, we can break it down into several key points:

### Step-by-Step Solution:

1. **Understanding the Visible Spectrum**:
- Red light and blue light are both part of the visible spectrum of electromagnetic waves. The visible spectrum ranges from approximately 400 nm (violet) to 700 nm (red).

2. **Wavelength**:
- Red light has a longer wavelength compared to blue light. Specifically, red light has a wavelength of about 620-750 nm, while blue light has a wavelength of about 450-495 nm.

3. **Frequency**:
- The frequency of light is inversely related to its wavelength. This means that as the wavelength increases, the frequency decreases. Therefore, red light, with its longer wavelength, has a lower frequency than blue light, which has a shorter wavelength.

4. **Speed of Light**:
- In a vacuum, the speed of light is constant for all colors of light, approximately \(3 \times 10^8\) m/s. However, when light travels through different media, its speed can change, but the speed remains the same for all colors in the same medium.

5. **Dispersion**:
- The difference in wavelength and frequency leads to different behaviors of light when passing through a medium. Blue light, with its shorter wavelength, is more susceptible to dispersion than red light. This is why the sky appears blue; blue light scatters more in the atmosphere than red light.

6. **Conclusion**:
- In summary, red light differs from blue light primarily in terms of wavelength and frequency. Red light has a longer wavelength and lower frequency, while blue light has a shorter wavelength and higher frequency.