speed of light in a medium?

Question

I know that as light enters a medium (from a vacuum) its wavelength is reduced and its frequency remains the same, resulting in a slower speed. But, can anybody explain to me exactly how the light is interacting with the atoms or molecules of the medium (whatever medium is preferred for an easy to understand explanation) in order for this to occur.

Answer 1

One way for you to understand this is to think of it this way:
Denser objects have more molecules in them, and since light is a transverse wave and it doesn't rely on transfer of energy between molecules to travel, it slows down because there's more stuff hitting it.

If you wanna get more technical about it, this is what happens to the actual photons of light:
Every time a photon hits an atom, that atom will "absorb" the photon and excite an electron. That electron will release the energy in the form of another photon after a minuscule amount of time. With objects that are denser, there are more atoms and molecules to absorb photons and release them, which takes time, causing light to "slow down". (note that light still travels at the speed of light between molecules, but it loses some time every time it's absorbed by a molecule, so its "average speed" slows down, but it still travels at the speed of light from atom to atom)

I hope this helped!

Answer 2

The first answerer (Pedros 20) has a great explanation. Kudos to you. The person who is asking the question has some ideas mixed up.

Wavelength determines frequency. If the wavelength shortens the frequency increases. If the wavelength lengthens the frequency decreases.

Velocity remains the same (between atoms/molecules).... the frequency changes probably due to the absorption of the photon and it's controlled release by the electron shell orbit of the atom. When the photon is absorbed, the orbital diameter increases a little. When the photon is released the orbit drops back down to the un-excited state. The further out the orbit, the higher the energy level it is released at.

Specific elements release photons at select frequencies or group of frequencies. (This is the whole idea in which a laser light emits a specific wavelength, high intensity, and a focused beam) Looking at how lasers operate my help you to understand what Pedros and I are talking about in more simplistic terms.

Also photo spectrophometry looks at the distant stars to see what they are made up of since atoms of many elements in the periodic table emit specific wavelength bands in the color spectrum that makes the elements easily identifyable hundreds of lightyears away from the source. All of this based on the absorption of photons and their release by orbital colapse back to it's unexcited state..

Answer 3

Light is defined as electromagnetic energy or radiation, composed of photons. Photons entering into a medium from a vacuum can do so from varying frequencies and wavelengths.

The problem is light permeates different elements in different ways or it cannot permeate at all and converts to heat or energy. Depending on frequency and wavelength.

Since photons have properties similar to both matter and energy, light interacts with matter in different ways.

When photons are introduced to matter they are either absorbed thereby transfering momentum and energy proportional to the frequency of the light entering the medium (m (0) v (c) = f (e) where mass of the photon is zero, velocity is the constant speed of light in a vacuum and force is measured as energy released. Think of a solar vane where there are fins with black and white sides to them. When the light strikes the black fins, the vane turns because the black side absorbs the photon's impact which is converted into force or energy. When it strikes the white fins, the light is reflected. By alternating the fins, the vane turns evenly.

As I said before the photon has both electromagnetic wave and particle properties.

What makes light neat is that the shorter the waves, the higher the frequency, the more matter the photon can penetrate. X-rays penetrate aluminum and other objects like skin and wood, for instance.

Answer 4

its like mike Tyson trying to punch though blancmange.