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Light is a primary tool for perceiving the world and interacting with it for many organisms. Light from the Sun warms the Earth, drives global weather patterns, and initiates the life-sustaining process of photosynthesis; about 10 22 joules of solar radiant energy reach Earth each day.
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Light is very important to life on Earth. Using the energy...
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Aug 19, 2024 · Understanding why light is so important can help us appreciate its role in our daily lives, as well as its impact on our health and the environment. In this article, we will explore the various ways light affects us, addressing common concerns about artificial lighting and its effects on sleep and mood.
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- 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.
Dec 29, 2017 · Sunlight helps keep nature clean. Due to drying, weeds, algae, and other microbes do not grow, keeping the environment clean and tidy. Even dead bodies and other waste materials get dried, lose their wet mass, and degrade fast. 6. Maintenance of temperature. Light energy from the sun raises the temperature of the earth. Due to this, life exists ...
Light is very important to life on Earth. Using the energy of light, plants combine a gas in the air called carbon dioxide with water in the soil. Through this process, called photosynthesis, plants make their own food. People and other animals then use plants for food. As plants make food, they also give off a gas called oxygen. People and ...
Without light the living things now on Earth would be unable to survive. Light from the Sun provides energy for life on Earth. Plants change the energy of sunlight into food energy. When light rays strike a green plant, some of their energy is changed to chemical energy, which the plant uses to make food out of air and minerals.
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Jan 22, 2024 · Light energy is a fascinating form of energy that travels through space. It behaves in unique ways and comes in different types that make up the electromagnetic spectrum. The Nature of Light. Light has a dual nature. It acts as both waves and particles called photons. This strange behavior helps explain how light moves and interacts with matter.
