Preview

Speed of Light

Good Essays
Open Document
Open Document
551 Words
Grammar
Grammar
Plagiarism
Plagiarism
Writing
Writing
Score
Score
Speed of Light
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.[2] 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.[3]
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

You May Also Find These Documents Helpful

  • Good Essays

    Motion - it's everywhere in the universe. Nothing is really standing still. We humans ride on a sphere that spins on an axis as it revolves around a star, a rotating star in orbit with 100 billion other stars in a whirling galaxy that's moving over 1 million kilometers an hour in an expanding universe. Some of this motion can be viewed over the course of a few minutes, and some requires centuries or millennia to be perceived.…

    • 478 Words
    • 2 Pages
    Good Essays
  • Good Essays

    1310 unit 4

    • 440 Words
    • 2 Pages

    Wavelengths of Light: The distance and electromagnetic wave travels in the time it takes to oscillate through a complete cycle.…

    • 440 Words
    • 2 Pages
    Good Essays
  • Better Essays

    Nt1310 Unit 7 Exercise 1

    • 580 Words
    • 3 Pages

    Refraction- deflection from a straight path undergone by a light ray or energy wave in passing obliquely from one medium (as air) into another (as glass) in which its velocity is different…

    • 580 Words
    • 3 Pages
    Better Essays
  • Good Essays

    Chemistry

    • 1374 Words
    • 6 Pages

    where is the speed of light (). The energy ( in joules) contained in one quantum of electromagnetic radiation is described by the equation…

    • 1374 Words
    • 6 Pages
    Good Essays
  • Satisfactory Essays

    Sun and Points

    • 496 Words
    • 2 Pages

    2. The speed of light indicates how fast light can travel in a vacuum. (6 points)…

    • 496 Words
    • 2 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Einstein's theory states that, the speed of light becomes a sort of ultimate speed limit. In fact, objects with mass, be they cars or neutrinos, can't reach the speed of light because they would need infinite energy to do so, according to the theory.…

    • 256 Words
    • 2 Pages
    Satisfactory Essays
  • Better Essays

    Properties of Light

    • 1269 Words
    • 6 Pages

    A three-sided enclosure from the cardboard box was made. This created a location for applying light from the LED to the drop of alcohol while minimizing the effect of air currents on the evaporation rate. The eyedropper was used to place a single drop of isopropyl alcohol on an index card within the enclosure. The same size drop was used each time the step was repeated. The time it takes for the drop to evaporate without the LED present was recorded. The dark spot on the card caused by the alcohol was no longer visible. A flashlight was used to help with the observance of the dark spot. The evaporation time was recorded. The same procedure was repeated for the different colored LEDs over the alcohol drop. The current through each LED and the distance from the LED to the drop of alcohol was the same for each run. The procedure for each color of LED was repeated at least 10 times and an average time of evaporation for each color was calculated. A graph of evaporation time versus frequency of the LED was then made.…

    • 1269 Words
    • 6 Pages
    Better Essays
  • Good Essays

    The angle of incidence (formed by the ray of light travelling though air into a slab of rectangular perspex) is not directly proportional to the angle of refraction (angle formed between the ray travelling though perspex and the normal). The graph of the plotted angles of incidence against the angles of refraction is not a straight line and therefore demonstrates this. However, a constant can be found by the formula sin i / sin r which is the specific refractive index for a particular medium eg. glass. Once the refractive index of a certain medium is known, the angle of refraction can be calculated if the angle of incidence and known and vice versa. The denser the medium, the larger the refractive index. Usually, the angle of incidence is larger than the angle of refraction when a ray of light is travelling from a less dense medium to a denser one.…

    • 647 Words
    • 3 Pages
    Good Essays
  • Good Essays

    As an object approached the speed of light it becomes more and compressed (It occupies less and less space), distorts the fabric of space time and time slows on the speeding object when compared to an object stationary state, it left at its source.…

    • 608 Words
    • 3 Pages
    Good Essays
  • Satisfactory Essays

    Prism reflecting Light

    • 333 Words
    • 2 Pages

    If I shine a light ray into a glass block then the light would be refracted. It will bend either away or towards the normal. This is because glass is more dense than air so the ray will be refracted by the change in density.…

    • 333 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    Big Bang Theory

    • 732 Words
    • 3 Pages

    5. light years- a unit of Astronomical distance equivilant to the distance that light travels in one year. The closest star is 4.37 light years away from earth…

    • 732 Words
    • 3 Pages
    Good Essays
  • Better Essays

    redshift and therefore the faster it moves away from us. The velocity of galaxies that are…

    • 1138 Words
    • 5 Pages
    Better Essays
  • Good Essays

    This number we found for the speed of light was 2.3498713 x 108. This is pretty close actual…

    • 430 Words
    • 2 Pages
    Good Essays
  • Good Essays

    Light when travelling in the electromagnetic spectrum in a void always has a constant speed of 3x108 m/s. When this passes through a solid or liquid which consists of a…

    • 1137 Words
    • 5 Pages
    Good Essays
  • Powerful Essays

    ocs 2007

    • 1724 Words
    • 6 Pages

    5. What is a light year and why do we use it to measure distance in the universe?…

    • 1724 Words
    • 6 Pages
    Powerful Essays