Light

Physical Science - Middle School

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2:13 1 2 3 4 5 6 7 8 9 0 Visible Light radio waves microwaves X-rays ultraviolet infrared gamma rays 1 + - - + 2 3 4 5 6 7 8 9 0 Electromagnetic Spectrum image plane mirror object virtual image object convex lens focal point focal point (less than 1 focal length from lens) concave lens focal point focal point object virtual image focal point front of mirror back of mirror real image object optical axis front of mirror back of mirror focal point virtual image object optical axis What Is Light? Light is everywhere. It is produced by luminous objects, such as fires, light bulbs and the Sun. Unlike sound, light does not require matter through which to travel, and it can travel through a vacuum such as space. Light travels at 300 million m/s, faster than anything scientists have yet to discover. Light is an electromagnetic wave that is made of vibrating electric and magnetic fields which are at right angles to each other. The light that we can see is called visible light, but there is also light that we cannot see, including ultraviolet light and infrared light. Visible light makes up just a small part of the electromagnetic spectrum, but it too can be broken up into different wavelengths. When passed through a glass prism, an ordinary light beam refracts into the many different colors or wavelengths of light. Light and Color The three primary colors of light are red, green and blue. The combination of these primary colors produces white light. Reflection of Light Refraction of Light Plane Mirrors Light that bounces off surfaces is called reflection. Because mirrors reflect light evenly, we can see an image in them. A mirror with a flat surface is called a plane mirror. It is usually made from a sheet of flat glass, with a thin coating of aluminum or silver on the back to reflect the light. Concave Mirrors A mirror with a surface that curves inward is called a concave mirror. The type of image formed by a concave mirror depends on the optical axis, focal point and focal length of the mirror. Convex Mirrors A mirror with a surface that curves outward is called a convex mirror. The image formed by a convex mirror is right side up but smaller than the original. Although light normally travels in straight lines, it can bend at the boundary between two materials with different densities. This is called refraction. Lenses Convex Lens A convex lens is thicker in the middle than around the edges. Convex lenses form different kinds of images depending on the distance between the object and the lens. Concave Lens A concave lens is thinner in the middle than around the edges. The image formed by a concave lens is virtual and smaller than the object. The color of an object is determined by the wavelengths of light that reach our eye. A red-colored object appears red because only red light is reflected while the other colors of light are absorbed. Objects appear black because they absorb all the colors of light, while white objects appear white because they reflect all the colors of light. red blue green yellow magenta cyan Focal point is behind the mirror. Image is always upright and reduced. glass air air Light © Copyright NewPath Learning. All Rights Reserved. 94-4810 www.newpathlearning.com
image plane mirror object virtual image object convex lens focal point focal point (less than 1 focal length from lens) concave lens focal point focal point object virtual image focal point front of mirror back of mirror real image object optical axis front of mirror back of mirror focal point virtual image object optical axis 2:13 1 2 3 4 5 6 7 8 9 0 Visible Light 1 + - - + 2 3 4 5 6 7 8 9 0 Concave Mirrors What Is Light? Light is everywhere. It is produced by luminous objects, such as fires, light bulbs and the Sun. Unlike sound, light does not require ________________ through which to travel, and it can travel through a vacuum such as space. Light travels at _______________ faster than anything scientists have yet to discover. Light is an ________________ __________ that is made of vibrating electric and magnetic fields which are at right angles to each other. The light that we can see is called _____________ _____________ , but there is also light that we cannot see, including _____________ ____________ and ____________ ____________ . Visible light makes up just a small part of the __________________ ______________ , but it too can be broken up into different ______________. When passed through a glass prism, an ordinary light beam ______________ into the many different _____________ or ______________ of light. Light and Color The three primary colors of light are _________ , __________ and __________ . The combination of these primary colors produces ______________ ______________ . Reflection of Light Refraction of Light Plane Mirrors Convex Mirrors Refraction Lenses Convex Lens Concave Lens The color of an object is determined by the ___________________ of light that reach our eye. A red-colored object appears red because only __________ light is reflected while the other colors of light are absorbed. Objects appear black because they _______________ all the colors of light, while white objects appear white because they _______________ all the colors of light. Describe a plane mirror: ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ Describe refraction: ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ Describe a concave mirror: ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ Describe a convex lens: ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ Describe a convex mirror: ___________________________ ___________________________ ___________________________ ___________________________ Describe a concave lens: ___________________________ ___________________________ ___________________________ ___________________________ Key Vocabulary Terms absorb concave lens concave mirror convex lens convex mirror electromagnetic wave focal length focal point gamma rays light magnetic field microwaves optical axis plane mirror primary colors radio waves reflection refraction ultraviolet light visible light wavelength x-rays \|xiBAHBDy01804pzY Light © Copyright NewPath Learning. All Rights Reserved. 94-4810 www.newpathlearning.com red blue green yellow magenta cyan