Question

Which colour of white light travels fastest, in glass?

• A. Red
• B. Violet
• C. Yellow
• D. All of the above travels with same velocity

Answer 1

The correct option is A Red

The velocity of light is given by v= $f\lambda$ where $f$ is the frequency and $\lambda$ is the wavelength.
When travelling through a medium the frequency remains unchanged and hence, speed depends upon the wavelength of light. Red light having maximum wavelength travels fastest.