# Why Does Light With Less Wavelength Run Faster in Glass?

• Hepic
In summary, light travels slower in glass due to its interaction with the molecules in the material. The shorter the wavelength of light, the faster it will travel in glass. The velocity of light in glass is inversely proportional to its wavelength, meaning that as the wavelength decreases, the speed of light increases. The refractive index of glass, which measures the speed of light in the material compared to vacuum, can also affect the speed of light. It is possible to alter the speed of light in glass by changing the properties of the material or using specialized materials such as metamaterials.

#### Hepic

1)I know that light with more wavelength run faster in the glass from an other with less.But why? If you tell me because has less diffract I will ask again,why it has less?

Watch these public outreach lectures on QED by Feynman.

http://vega.org.uk/video/subseries/8

The second one, I think, contains a section on diffraction, specifically. He also talks at length about the question of "what does it mean".

## 1. Why does light travel slower in glass?

Light travels slower in glass due to the interaction between the light and the molecules in the glass. The molecules absorb and re-emit the light, causing it to take longer to travel through the material.

## 2. How does the wavelength of light affect its speed in glass?

The wavelength of light plays a significant role in its speed in glass. Light with shorter wavelengths, such as blue or violet light, will travel faster in glass compared to light with longer wavelengths, such as red or orange light.

## 3. What is the relationship between wavelength and velocity of light in glass?

The velocity of light in glass is inversely proportional to its wavelength. This means that as the wavelength decreases, the velocity of light increases in glass.

## 4. What is the refractive index of glass and how does it affect light speed?

The refractive index of glass is a measure of how much slower light travels in the material compared to in a vacuum. The higher the refractive index, the slower the speed of light in glass. This is because a higher refractive index indicates a stronger interaction between light and the molecules in the material.

## 5. Can the speed of light in glass be altered?

Yes, the speed of light in glass can be altered by changing the properties of the glass, such as its composition or temperature. This can also be achieved by using specialized materials, such as metamaterials, which can manipulate the speed of light in unique ways.