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Slow light is a dramatic reduction in the group velocity of light, not the phase velocity. Slow light effects are not due to abnormally large refractive indices, as will be explained below. The simplest picture of light given by classical physics is of a wave or disturbance in the electromagnetic field.
For example, for visible light, the refractive index of glass is typically around 1.5, meaning that light in glass travels at c / 1.5 ≈ 200 000 km/s (124 000 mi/s); the refractive index of air for visible light is about 1.0003, so the speed of light in air is about 90 km/s (56 mi/s) slower than c.
The speed of this flow has multiple meanings. In everyday electrical and electronic devices, the signals travel as electromagnetic waves typically at 50%–99% of the speed of light in vacuum. The electrons themselves move much more slowly. See drift velocity and electron mobility.
The light has effectively been slowed. When light returns to a vacuum and there are no electrons nearby, this slowing effect ends and its speed returns to c. When light enters a slower medium at an angle, one side of the wavefront is slowed before the other. This asymmetrical slowing of the light causes it to change the angle of its travel.
Barring a freak power outage, the light emanating from towns and cities due to unnatural light sources is so bright that it washes out the stars. Today one-third of all humans, including 80% of ...
where c is the speed of light in vacuum, and n is the refractive index of the medium. In general, the refractive index is some function of the frequency f of the light, thus n = n(f), or alternatively, with respect to the wave's wavelength n = n(λ).
Experts explain why slow-burning can be healthy—and how to tell if it's holding you back. ... “There's this pressure on women that it’s going to be automatic, but it takes time to get to ...
Here's a question: Why is my computer so slow? The answer to this age-old question could be any number of things. So, I'm going to identify a few steps you can take to hopefully remedy the ...