What is the ratio of velocity of red colour light to velocity of violet colour of light in vacuum ?

Answer

To find the ratio of the velocity of red light to the velocity of violet light in vacuum, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the velocities of light in vacuum**:
- The speed of light in vacuum is a constant value for all colors of light. It is approximately \( c = 3 \times 10^8 \) meters per second.

2. **Identify the velocities of red and violet light**:
- Velocity of red light in vacuum, \( v_{red} = 3 \times 10^8 \) m/s.
- Velocity of violet light in vacuum, \( v_{violet} = 3 \times 10^8 \) m/s.

3. **Set up the ratio**:
- The ratio of the velocity of red light to the velocity of violet light can be expressed as:
\[ \text{Ratio} = \frac{v_{red}}{v_{violet}} = \frac{3 \times 10^8 \text{ m/s}}{3 \times 10^8 \text{ m/s}} \]

4. **Calculate the ratio**:
- Simplifying the fraction gives:
\[ \text{Ratio} = 1 \]
- Therefore, the ratio can be expressed as:
\[ \text{Ratio} = 1 : 1 \]

5. **Conclusion**:
- The ratio of the velocity of red light to the velocity of violet light in vacuum is \( 1 : 1 \).