The velocity of light in vacuum can be changed by changing

Options

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

Answer

To solve the question regarding the factors that can change the velocity of light in a vacuum, let's analyze the options provided:

1. **Understanding the nature of light in a vacuum**:
- Light travels at a constant speed in a vacuum, which is approximately \(3 \times 10^8\) meters per second. This speed is denoted as \(c\).

2. **Analyzing the options**:
- **Frequency**: The frequency of light is related to its energy and is defined as the number of oscillations per second. Changing the frequency does not affect the speed of light in a vacuum.
- **Amplitude**: The amplitude of light relates to its intensity or brightness but does not influence its speed in a vacuum.
- **Wavelength**: The wavelength of light is inversely related to its frequency (as given by the equation \(c = \lambda f\)). However, in a vacuum, the speed of light remains constant regardless of changes in wavelength.
- **None of these**: Since none of the factors mentioned (frequency, amplitude, wavelength) can change the speed of light in a vacuum, this option seems to be the most appropriate.

3. **Conclusion**:
- The velocity of light in a vacuum cannot be changed by altering frequency, amplitude, or wavelength. Therefore, the correct answer is **none of these**.

### Final Answer:
The velocity of light in vacuum can be changed by changing **none of these**.