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Speed of Light
Denoted with the symbol "c," the speed of light is 299,792,458 metres per second and is often rounded as 300,000 kilometres per second or 186,000 miles per second.
1,290 Questions
What is the exact speed of light?
The exact speed of light in a vacuum is approximately 299,792 kilometers per second or about 186,282 miles per second.
What is the formula for the speed of light?
The speed of light can be measured in miles (as we do here in the US) as: 186,000 miles per second (which means light can circle the earth over seven times every second!), or 5,865,696,000,000 miles per year (which, to spare you from counting the digits, is just under 6 trillion miles per light year!).
THE SPEED OF LIGHT is 299,792,458 meters per second - in a vacuum or 186,282 miles per second in a vacuum. And according to the theories of motion - nothing can travel faster than the speed of light. If it does - it bends time and time will slow down and eventually - as the speed increases - time will start going backward - and you will travel back in time!!! And of course this is theory - it has never been tested - as the fastest movement - relative to the person measuring the movement) has never even approached 50% (93,000 miles per hour) of the speed of light!!!!
The speed of light - as all speeds are measured - is determined by the distance travelled - divided by the amount of time it took to travel that distance. A race car, for example, measures it's speed by the amount of time to travel a specific known distance (quarter mile - or 500 miles) divided by the time it took to travel that distance.
The speed of light is something we've figured out only in the last 100 years, right? Well, once more, our forebears surprise us. It turns out we've known the speed of light since before the birth of Johann Sebastian Bach.
That knowledge came close on the heels of the invention of the first telescopes in the early 1600s. In 1644, Ole Roemer was born in Jutland, Denmark. He took up the new study of astronomy with the early greats of that field.
By 1675 Roemer was 31 and working in Paris with Picard. He was interested in the movement of Jupiter's nearest moon. He tracked it as it orbited in and out of Jupiter's shadow. It entered the shadow, then reemerged exactly 42 hours, 28 minutes, and 35 seconds later. It moved with constant and exact regularity.
So Roemer measured 100 cycles and found that in one hundred cycles, Jupiter's moon could be relied upon to emerge EVERY TIME - right on schedule - to the exact second!! So he measured different lengths of time!! One was six months -- 100 laps -- and it was then that Roemer set his clocks and focused his telescope on Jupiter in the winter. In the spring - he waited and waited - but no moon appeared!! Finally it danced out of the shadows a full 15 minutes late. But why was the moon late - there MUST be a reason!!
After much discussion, Roemer concluded that the moon was still appearing at the same time - and it was the earth that had moved!! The earth had swung hundreds of millions of miles away from Jupiter during the long winter months so light had to travel that vast distance to see Jupiter's moon!!! It had obviously taken the extra time to do so. (Also discovering that earth's orbit around the sun is egg-shaped - NOT a circle!!)
He put pencil to paper and concluded that light had to move 192,500 miles per second to lose just those fifteen minutes. Not bad at all! Roemer was within three percent of the right value (186,282 miles per second). And that was less than 70 years after we first had telescopes.
Just to be sure, Roemer calculated when we'd get that 15 minutes back, as the earth moved back toward Jupiter and spring began. He was right again.
Today the speed of light is measured - and found to be accurate - by pointing a laser to one of the many groups of mirrors and reflectors that were set up on the moon by the 1970's moon landing missions. Now computers accurately measure the speed light with a laser - and can determine the exact speed of light to within 1/quadtrillionth of a second!!! These mirrors also measure the movement of earthquakes on the earth - from the moon - to within 1/10,000,000,000th of an inch!!!!
Hope this helps - and hope you enjoy science!!!!!
What is light speed in km min-1?
Hmm, I don't know what the speed of light is in kilometers per hour but I do know what it is in Kilometers per second which is 300.000 km/sec (3x10^5 - 3 with 5 zeros)
Let's see what that translates to if we convert that to km/hr.
300.000 (km/sec) X 3600(seconds in 1 hour) = 1.080.000.000
There you have it. The speed of light is 1.080.000.000 (One-billion-eighty-million)
km/hr.
If you want to write that down in a scientific manner, you should write 1,08x10^9
Whats the difference between reflection and refraction?
Reflection is the bouncing back of light waves off a surface, whereas refraction is the bending of light waves as they pass through a medium of different optical density. Reflection occurs when light hits a boundary and bounces back, while refraction happens when light passes through a boundary and changes direction.
What is it that travels through an electric circuit at nearly the speed of light?
the wave front of electric current. the electrons themselves move much slower but they keep pushing electrons ahead of them on resulting in a wavefront that moves at almost the speed of light.
Does light wave travel through air at a faster speed than sound?
Yes! Sound has to have a medium such as air to travel. That's why there is no sound in space. So, if you stood on the surface of the earth and yelled very loudly straight up, the sound would stop after about 300 miles, because our atmosphere is only 300 miles thick. When the air runs out, the sound stops. BUT, if you shine a very bright light straight up, the light could go much, much further, because light CAN travel through the vacuum of space. That's how we can see stars that are trillions of miles away, because of the light they shine in our direction.
What are the fundamental quantities?
The fundamental quantities are physical quantities that are independent and cannot be derived from any other physical quantities. There are seven fundamental quantities in the International System of Units (SI): length, mass, time, electric current, temperature, amount of substance, and luminous intensity.
Can electricity travel at the speed of light?
Electromagnetic waves propagate at or near the speed of light, since photons are the carrier of the electromagnetic force, however electricity (that is, the transfer of electrons in a coil or wire) travels quite a bit slower
Electrons will vibrate in the coil at "Fermi velocity" which is 1500000 m/s for electrons, but will actually travel the length of the wire at .0003 m/s
So, usually no, electricity does not travel at the same speed as light.
What is the frequency of a gamma ray?
Gamma rays are radiation from nuclear decay, when a nucleus changes from an excited energy state to a lower energy state. Gamma rays are typically waves of frequencies greater than 1019 Hz. They have high energies (greater than 104 eV per photon) and extremely short wavelengths (less than 10-14 m). Gamma rays can penetrate nearly all materials and are therefore difficult to detect. Gamma rays have mostly been detected in the activities in space such as the Crab Nebula and the Vela Pulsar. The highest frequency of gamma rays that have been detected is 1030 Hz measured from diffuse gamma ray emissions.
From the PHYSICS FACTBOOK
Why can't an object with mass travel at the speed of light?
According to Einstein's physics, it would require an infinite amount of energy to accelerate a mass to the speed of light. Unless we invent warp drive, it ain't gonna happen. ================================== My high school physics teacher explained that it's like pushing wagon up a hill. As you get closer to the speed of light, the wagon becomes a car. As you get even closer to the speed of light, the car becomes a truck, becomes a bus, etc.
E=mc^2
Mass grows as you approach the speed of light. Therefore, more energy is required to move the ever increasing mass.
What is the speed of light on Mars?
Sound always travels at the same speed.
The speed of sound varies by medium and temperature. Aerospaceweb seems to conclude that the speed of sound on the surface of Mars is roughly 550 mph.
What is the abbreviation of speed?
The abbreviation for speed is S= d/t which is Speed = Distance/ Time
What happens if you are driving a car at the speed of light and you cut your headlights on?
It's impossible for any object with mass to travel at the speed of light. Due to the laws of physics, the concept of mass and energy at the speed of light does not follow our everyday experience. Therefore, the scenario of turning on headlights while moving at the speed of light cannot be realistically described.
A measure of the quantity of matter is?
The measure of the quantity of matter is mass. Mass is a fundamental property of an object that determines its resistance to acceleration. It is typically measured in units such as kilograms or grams.
Speed of light in miles per hour?
We don't know what "hour second" means, and have a nagging suspicion
that it's quite meaningless.
In vacuum, the speed of light is roughly
-- 186,282 miles per second
-- 670,615,200 miles per hour
-- 16,094,764,800 miles per day
-- 112,663,353,600 miles per week
-- 5,878,715,206,000 miles per year.
Why Diamond is the hardest substance?
Diamond is no longer the hardest known substance. Several new compounds have beaten it.
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Because only another diamond can scratch another diamond. Also they use diamond made drills. My daddy told me that. But it is the hardest. My friend Joshua told me that about the only thing that scratch it. I thought the pavement was the hardest.
From Marlon
What is the Microwave disadvantages?
In terms of microwaves themselves, the dangers are largely limited to the effects of the heat generated when the microwaves interact with human tissue. The greatest risk of high power microwaves is to the eyes, where the heat cannot be quickly removed by the cooling effect of the blood supply. Hence, corneas are particularly vunerable to micriwave heating. The testes in males are also vulnerable, although it is generally less likely that they will be exposed to microwaves.
In terms of microwave oven use, there are two principle dangers - The first is superheated liquids (liquids above their normal boiling point), which can flash-boil when, for example, instant coffee, sugar, or any other power is added. The second (and at one time the cause of most microwave oven accidents) comes from exploding unbroken eggs, as the yolk heats so efficiently that, even if the egg doesn't explode in the microwave, it can explode in the user's face when it is removed from the microwave oven.
There are no reliable reports of adverse health effects from low-level microwaves from such things as mobile phones or telecom masts.
What happens to speed of light when light goes into air?
That depends what it comes out of. If it passes into air from vacuum, then
its speed decreases. If it passes into air from water or jello, then its speed
increases.
What are typically filled with argon?
Argon gas is typically filled in light bulbs to prevent oxidation of the filament and extend the bulb's life. It is also used in double-pane windows to improve insulation by reducing heat transfer. Additionally, argon is commonly used in welding to displace air and prevent oxidation of the metal being welded.
The speed of light is 300000000 in a vacuum.Does it always have this speed?
The speed of light is exactly fixed at 299,792,458 m/s in the vacuum of freespace. It is an important physical constant usually denoted by the symbol c0. There is nothing faster. Light has always this speed in a vacuum, but it slows down when it travels through something, like glass, water, or air ... The greater the density of the matter that light is travelling through, the slower light travels.
What if speed of light was 761 MPH?
The visual and audio components of an event would reach you at the same time regardless of distance. For example when you see lightning strike in the distance, and it takes awhile to hear the thunder. If light traveled at 761, you would see, and hear it simultaniously.
What if the speed of light traveled at the speed of sound?
If the speed of light traveled at the speed of sound, our entire perception of the universe would drastically change. The fast travel and instant communication enabled by the speed of light would no longer be possible, leading to a significant impact on technology, communication, and our understanding of the cosmos. The universe would appear much different to us due to the altered timeframes and distances involved.
The speed of light isn't represented by an equation; it is represented by the letter c. c figures in many applications in physics, so you would have to be more specific about what you are looking for.
What is the symbol for the speed of light?
Normally its a lowercase c, as in E=m(c)2. Energy=mass times the speed of light squared.
