Does light regain the speed after passing through denser medium?

[Vasant Sundar]

I went through the opinions expressed by individuals in this regard. But they seem to be inconclusive. How a lost speed can be regained after exiting the denser medium?

If so we may conduct the same good old experiment for fringe measurements in light interference theory.

First fix the locations of the fringes by conducting normal experiment with mono chromatic light. Then put one glass slab in one of the paths of interfering light beams. The light beams will no longer coincide at the same locations. The fringes will shift.

They will shift back and forth with glass slab thickness.

Sounds OK?

[beer4life]

I went through the opinions expressed by individuals in this regard. But they seem to be inconclusive. How a lost speed can be regained after exiting the denser medium?

If so we may conduct the same good old experiment for fringe measurements in light interference theory.

First fix the locations of the fringes by conducting normal experiment with mono chromatic light. Then put one glass slab in one of the paths of interfering light beams. The light beams will no longer coincide at the same locations. The fringes will shift.

They will shift back and forth with glass slab thickness.

Sounds OK?

G'Day Cobber,
I rather doubt it as the thickness of a slab of glass is infinitesimal with regard to the speed of light. (300,000 KMs/ second). I'll let you work that out. My bank of computers ran out of the powers of.
Methinks you would only get a phase shift.

[porkop]

The speed of light changes with the refractive index of the material, much like the velocity factor of coax cable.

so as light passes from one medimum of RI x into a medium of RI y then passes back to medium with RI x again, it is safe to say that it will alter its speed from one to the other and back again.

this was year 11 physics!!!

[Fernbay]

It's best to report spammers and trolling rather than feeding them guys

I'll close this as the chances of it being a genuine topic of intrest to the single post original poster are less than 10%.

It is simply a post designed to up the users post count in preperation for later spamming.

I'm suprised that the OP hasn't added spam links to their signature yet.


I'll close this as I would suggest most of our members have a firm grasp of junior high school physics, including observing blue shift, red shift, rainbows, sun rise and sunsets.

Just on the off chance the OP is genuine.....

The speed of light (meaning speed of light in vacuum), usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time.[1] This speed is approximately 186,282 miles per second. It is the maximum speed at which all energy, matter, and information in the universe can travel. It is the speed of all massless particles and associated fields—including electromagnetic radiation such as light—in vacuum, and it is predicted by the current theory to be the speed of gravity (that is, gravitational waves). Such particles and waves travel at c regardless of the motion of the source or the inertial frame of reference of the observer. In the theory of relativity, c interrelates space and time, and appears in the famous equation of mass–energy equivalence E = mc2.[2]

The speed at which light propagates through transparent materials, such as glass or air, is less than c. The ratio between c and the speed v at which light travels in a material is called the refractive index n of the material (n = c / v). 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; the refractive index of air for visible light is about 1.0003, so the speed of light in air is about 90 km/s slower than c.

In most practical cases, light can be thought of as moving instantaneously, but for long distances and very sensitive measurements the finite speed of light has noticeable effects. In communicating with distant space probes, it can take minutes to hours for the message to get from Earth to the spacecraft and back. The light we see from stars left them many years ago, allowing us to study the history of the universe by looking at distant objects. The finite speed of light also limits the theoretical maximum speed of computers, since information must be sent within the computer from chip to chip. Finally, the speed of light can be used with time of flight measurements to measure large distances to high precision.

Ole Rømer first demonstrated in 1676 that light travelled at a finite speed (as opposed to instantaneously) by studying the apparent motion of Jupiter's moon Io. In 1905, Albert Einstein postulated that the speed of light in vacuum was independent of the source or inertial frame of reference, and explored the consequences of that postulate by deriving the theory of special relativity and showing that the parameter c had relevance outside of the context of light and electromagnetism. After centuries of increasingly precise measurements, in 1975 the speed of light was known to be 299,792,458 m/s with a relative measurement uncertainty of 4 parts per billion. In 1983, the metre was redefined in the International System of Units (SI) as the distance travelled by light in vacuum in 1⁄299,792,458 of a second. As a result, the numerical value of c in metres per second is now fixed exactly by the definition of the metre.[3]