# What is the nature of refraction ?

• blenx
In summary, when light passes from a vacuum to a medium, the atoms of the medium bend the light towards a certain direction according to Snell's law.

#### blenx

Take Electromagntic wave for example , when light pass from vacuum to one medium , how does the atoms of the medium bend the light towards a certain direction at the microscopic level ?

As far as I know, when light changes from medium to another medium (i.e. a difference in the density of the substance) the light will change its speed as well. At the time it changes the speed it will also bend according to the Snell's law. So my advice if you really want to know the nature of Snell's law is to read an article about it.

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blenx said:
Take Electromagntic wave for example , when light pass from vacuum to one medium , how does the atoms of the medium bend the light towards a certain direction at the microscopic level ?

By reducing the speed of propogation from c_0 to c_0/n. Momentum is conserved, so the direction of propagation changes.

If you think of light in terms of particles, then it's because of conservation of momentum.

If you don't want to use conservation of momentum, you can think of light in terms of a wave. You can try an experiment - Put thin oil and water into a container and separate them by a very thin plastic film. If you make a wave in one fluid you will see the wave 'change direction' slightly when it hits the other fluid, because of speed changes.

I have learned electrodynamics , whose explanation of refraction I think is quite phenomenological. Because it have not touched on the microscopic details when light enter the medium .

It is certain that the bending of light must be due to the interaction between photon and atoms , but I don't think the speed of photon will be slowed down after the interaction at the microscopic level . The slowdown of a light wave is a macroscopic phenomenon which invlove with lots of microscopic details . In this sense , conservation of momentum cannot ensure the photon will turn to a certain direction after interaction . It's possible for the phton turn to another direction and the momentum conservation law also holds .

So, what is the root cause of refraction ?

I have wondered this my self , and most people say the speed changes , but we all know that light always travels at c , so the speed is not changing , it is just the time lag from it interacting with the electrons and other stuff it is pretty complicated but anyways , when white light hits the glass why do the red photons take a different angle then the blue photons .

## 1. What is refraction?

Refraction is the bending of light as it passes through different mediums, such as air, water, or glass.

## 2. How does refraction occur?

Refraction occurs when light travels through a medium with a different density than the medium it was previously traveling through. This change in density causes the light to change speed and direction.

## 3. What is the cause of refraction?

The cause of refraction is the change in speed and direction of light as it passes through mediums with different densities. This change in density can be caused by different temperatures or compositions of the medium.

## 4. How is refraction measured?

Refraction is typically measured using the angle of incidence and the angle of refraction. The angle of incidence is the angle at which light enters a medium and the angle of refraction is the angle at which light exits the medium. The ratio of these angles can be used to calculate the refractive index, which is a measure of how much the light is bent.

## 5. What are some practical applications of refraction?

Refraction has many practical applications in our everyday lives. Some examples include eyeglasses, telescopes, cameras, and microscopes. It is also used in the design of lenses, prisms, and other optical instruments. Refraction is also important in understanding the behavior of light in different mediums, which is essential in fields such as meteorology and oceanography.