Question

In vacuum,

• A. speed of red light is equal to the speed of yellow light
• B. speed of red light is greater than the speed of yellow light
• C. speed of yellow light is greater than the speed of red light
• D. none of these

Answer 1

The correct option is A

speed of red light is equal to the speed of yellow light

Explanation of correct option:

1. Speed of electromagnetic wave in vacuum is $3\times {10}^8{\text{ms}}^{-1}$, for all possible frequency.
2. Red and yellow light are both electromagnetic waves but with different frequencies.
3. Therefore, the red and yellow light will have the same speed in a vacuum.

Final answer: In a vacuum speed of red light is equal to the speed of yellow light.
Hence, correct option is (a)