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Apr 30, 2018 · Physics extends well into your everyday life, describing the motion, forces and energy of ordinary experience. In actions such as walking, driving a car or using a phone, physics is at work. For everyday living, all the technologies you might take for granted exploit the rules of physics.
- Overview
- Ray theories in the ancient world
Light is electromagnetic radiation that can be detected by the human eye. Electromagnetic radiation occurs over an extremely wide range of wavelengths, from gamma rays with wavelengths less than about 1 × 10−11 metres to radio waves measured in metres.
What is the speed of light?
The speed of light in a vacuum is a fundamental physical constant, and the currently accepted value is 299,792,458 metres per second, or about 186,282 miles per second.
What is a rainbow?
A rainbow is formed when sunlight is refracted by spherical water droplets in the atmosphere; two refractions and one reflection, combined with the chromatic dispersion of water, produce the primary arcs of colour.
Why is light important for life on Earth?
While there is clear evidence that simple optical instruments such as plane and curved mirrors and convex lenses were used by a number of early civilizations, ancient Greek philosophers are generally credited with the first formal speculations about the nature of light. The conceptual hurdle of distinguishing the human perception of visual effects from the physical nature of light hampered the development of theories of light. Contemplation of the mechanism of vision dominated these early studies. Pythagoras (c. 500 bce) proposed that sight is caused by visual rays emanating from the eye and striking objects, whereas Empedocles (c. 450 bce) seems to have developed a model of vision in which light was emitted both by objects and the eye. Epicurus (c. 300 bce) believed that light is emitted by sources other than the eye and that vision is produced when light reflects off objects and enters the eye. Euclid (c. 300 bce), in his Optics, presented a law of reflection and discussed the propagation of light rays in straight lines. Ptolemy (c. 100 ce) undertook one of the first quantitative studies of the refraction of light as it passes from one transparent medium to another, tabulating pairs of angles of incidence and transmission for combinations of several media.
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With the decline of the Greco-Roman realm, scientific progress shifted to the Islamic world. In particular, al-Maʾmūn, the seventh ʿAbbāsid caliph of Baghdad, founded the House of Wisdom (Bayt al-Hikma) in 830 ce to translate, study, and improve upon Hellenistic works of science and philosophy. Among the initial scholars were al-Khwārizmī and al-Kindī. Known as the “philosopher of the Arabs,” al-Kindī extended the concept of rectilinearly propagating light rays and discussed the mechanism of vision. By 1000, the Pythagorean model of light had been abandoned, and a ray model, containing the basic conceptual elements of what is now known as geometrical optics, had emerged. In particular, Ibn al-Haytham (Latinized as Alhazen), in Kitab al-manazir (c. 1038; “Optics”), correctly attributed vision to the passive reception of light rays reflected from objects rather than an active emanation of light rays from the eyes. He also studied the mathematical properties of the reflection of light from spherical and parabolic mirrors and drew detailed pictures of the optical components of the human eye. Ibn al-Haytham’s work was translated into Latin in the 13th century and was a motivating influence on the Franciscan friar and natural philosopher Roger Bacon. Bacon studied the propagation of light through simple lenses and is credited as one of the first to have described the use of lenses to correct vision.
Higher energy light such as gamma rays, X-rays, and high energy UV light cause ionizations. They transfer enough energy to electrons so they can escape from the pull of the atom’s nucleus and turn the atom into an ion. Low energy UV and visible light cause electron transitions.
- The speed of light can change. The highest ever recorded is 299 792 458 m / s. In 1998, Danish physicist Lene Vestergaard Hau led a combined team f...
- yeah! for example some lightbulbs are more "warm" and orangy and some are more white
- Any kind of Electro-Magnetic wave travels in small energy packets called photons. In the visible range of light these are called photons and in the...
- actually, you thrown ball does make a wave. its just that the wavelength is so small, you could not observe or measure it DeBroglie said: Wavelengt...
- Photons can be absorbed by electrons. These will increase in energy and jump energy levels. Afterward, the same electron can emit the photon to jum...
- a wave can be described as the transmission of disturbance from one point to another OR the transmission of energy from on point to another
- it might be too late but ill try to answer. as per my understanding, a photon's energy is dependent only on its wavelength, that's what quantum mec...
- First you cannot treat the energy of a classical light wave the same way as the energy of a photon. The energy of a photon is E = hf. The energy of...
- c/v gives [m/s] / [Hz]. And knowing that Hz (Hertz) is equal to 1/s, then we have [m/s] / [1/s] which gives us after removing the seconds unit to g...
Jan 22, 2014 · An MIT physicist has proposed the provocative idea that life exists because the law of increasing entropy drives matter to acquire lifelike physical properties.
Light is a transverse, electromagnetic wave that can be seen by the typical human. The wave nature of light was first illustrated through experiments on diffraction and interference. Like all electromagnetic waves, light can travel through a vacuum. The transverse nature of light can be demonstrated through polarization.
Modern physics includes two revolutionary theories: relativity and quantum mechanics. These theories deal with the very fast and the very small, respectively. The theory of relativity was developed by Albert Einstein in 1905.
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Modern physics is a branch of physics that developed in the early 20th century and onward or branches greatly influenced by early 20th century physics. Notable branches of modern physics include quantum mechanics, special relativity and general relativity.
