Measuring the speed of light is not easy. Light travels at 300,000 kilometers per second (186,000 miles per second), which is far too fast to easily measure. Over the years, many scientists have made attempts to measure the speed of light, but it... read more
In several different ways, all of which give almost the same results. The method most easily explained is that used by a French scientist, Fizeau, in 1849. He had a wheel made with 720 teeth round the edge, separated by spaces of the same width as the teeth.
This was mounted in a way that enabled it to be turned steadily at any speed. A beam of light from a lamp was reflected from a mirror through the spaces between the wheel's teeth to another mirror set up about 5 1/3 miles away. The mirror near the wheel had a hole at the center so that an observer looking through it might watch the reflections of light from the distant mirror.
Fizeau found that when the wheel was run up to a certain speed no reflection of light could be seen. This meant that each flash passing through a gap was obstructed by the next tooth after traveling the 10 2/3 miles to the far mirror and back.
So, to find the speed of light, it was only necessary to multiply 10 2/3 miles by the number of times per second (about 18,144) that a gap was replaced by a tooth. The result, as you will find, if you care to work it out, is about 186,000 miles a second.
by Mishael Austin Witty 2 years ago
What is the speed of dark?My husband found this question in his fortune cookie tonight. Neither one of us knew how to answer it. And we certainly didn't know how it related to fortune. So, I thought it might be interesting to throw it out here and see others had to say.
by Aqeel Saeed 9 years ago
if it happens then just move in universe, today in ploto and the other day in other galaxy.
by Mikel G Roberts 6 years ago
If I was on a space ship traveling at the speed of light (The natural speed limit proposed by Einstein) and I fired a gun would the bullet remain in the gun?My belief is no it would not. I believe the bullet would leave the gun at the same increased velocity that it would achieve if I had fired the...
by Philip Cooper 3 years ago
Do you believe it will be possible to travel close to the speed of light?
by Irfan 5 years ago
Aircrafts have past the speed of sound ... do you think they will ever break the speed of light?Do you think the light barrier can be broken? ... I think it can.
by jomine 5 years ago
Suppose a light ray travelling near a black hole, which has so much gravity that the escape velocity is twice the speed of light, got caught in its gravitational field. Will the light travel at the speed of light or travel at double the speed of light?Similarly what happen to other objects...
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