In The Name Of Allah
قريبا ان شاء الله سأترجم هذا الموضوع الى العربية
What Is Light
Light is a type of energy caused by a combination of electrical and magnetic fields. Light travels as waves so it has typical wave features, such as wavelength. Light also behaves as a stream of tiny particles, called photons.
There are two types of light. Visible and Invisible light. Visible light is light in which the human eye can detect. Visible light can be refracted or reflected.
(1) Refracted Light:
Refracted light is light which has been bent out of its original path by passing through two different substances, such as air and a glass prism. When light passes through one transparent substance, such as air, to another, such as glass, it appears to bend where the two substances meet. This bending is called refraction. It happens because light has a different speed in each substance, or medium. Light travels fastest – the ‘speed of light’ – through space or a vacuum. It travels slightly more slowly through air. In water, it travels much more slowly, only about three quarters of its speed in a vacuum. In glass, it is slower still. Refraction is used in hundreds of devices, from contact lenses to giant telescopes. A spectrum is created from white light as it is refracted due to the different wavelengths or colours of light being slowed by different amounts.
(2) Reflected Light:
When light hits certain kinds of surfaces, it bounces back from the surface, like a ball bouncing off a wall. This is called reflection. Most objects do not give out their own light. We see them because they reflect light from something else, into our eyes. For example: The moon does not give off it’s own light. It shines because it reflects the suns light. A very smooth and shiny surface, for example: A mirror reflects most of the light hitting it, without scattering. So it produces a bright clear reflection. On a rough surface, light is reflected in all directions, producing poor reflections. The colors of objects also depend on reflections. A white object reflects all the colors of white light shining on it. A completely black object reflects no light at all.
(3) Invisible Light:
Invisible Light is light in which the human eye cannot detect; Because the wave length is either too long or too short. The two types we are focusing on are: Infrared Light and Ultra Violet Light (UV Radiation)
(4) Infra Red Light:
Infrared Light is light with a wave length just longer than that of red light, It’s wave length is between 0.0009 mm and that of short wave micro waves. Infrared light transmits heat, to other substances. It can be used to measure the temperature of the surrounding area. Scientists and Geologists use it to detect weather systems and measure temperature in the earth’s crust.
(5) Ultra Violet Light:
Ultra Violet Light is light with a wave length of just below.0004 mm. It is a harmful type of radiation which can damage chemical bonds in DNA. It can also harm the human eye and skin. We wear sunglasses with polarized lenses (see polarized light), it blocks out the ultraviolet radiation, protecting our eyes. We use sunscreen to protect our skin from UV Radiation.
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