Skip to main content. DigitalCommons University of Nebraska - Lincoln. Calculus-Based General Physics. Title Lenses and Mirrors. Abstract If you have ever worn glasses, used a magnifying glass, looked through a telescope, or looked in a mirror, you have some idea of the effect that transmitting and reflecting materials have on light.
Included in Other Physics Commons. Search Enter search terms:. Convex lenses The type of image formed by a convex lens depends on the lens used and the distance from the object to the lens.
A camera or human eye Cameras and eyes contain convex lenses. For a distant object that is placed more than twice the focal length from the lens, the image is: inverted upside down diminished smaller than the object real can be produced on a screen Ray diagram for an object placed more than two focal lengths away from a convex lens Projectors Projectors contain convex lenses.
For an object placed between one and two focal lengths from the lens, the image is: inverted upside down magnified larger than the object real can be produced on a screen Ray diagram for an object placed between 2F and F from a convex lens In a film or data projector, this image is formed on a screen. Magnifying glasses A magnifying glass is a convex lens used to make an object appear much larger than it actually is.
The image is: upright the right way up magnified larger than the object virtual cannot be produced on a screen Ray diagram for an object placed less than one focal length from a convex lens Only the person using the magnifying glass can see the image. Concave lenses Concave lenses always produce images that are: upright diminished virtual Peep hole lenses Peep holes are set into doors so the occupant can identify a visitor before opening the door.
Ray diagram for an object viewed through a concave lens For an object viewed through a concave lens, light rays from the top of the object will be refracted and will diverge on the other side of the lens. These rays will appear: from the same side of the principal axis meaning the image will be upright further from the principal axis, so the image will be larger than the object. A magnifying glass uses a convex lens because these lenses cause light rays to converge, or come together.
A magnifying glass, in effect, tricks your eyes into seeing what isn't there. Light rays from the object enter the glass in parallel but are refracted by the lens so that they converge as they exit, and create a "virtual image" on the retina of your eye. This image appears to be larger than the object itself because of simple geometry: Your eyes trace the light rays back in straight lines to the virtual image, which is farther from your eyes than the object is and thus appears bigger.
The magnifying lens is a critical aspect of modern technology. Without it, you would not be able to take advantage of cameras, watch movies on a screen or use gadgets such as the night-vision goggles that are vital in certain military operations. Going back to the early 17th century, Galileo assembled the first astronomical telescope, and discovered previously unknown features of Earth's moon and nearby planets, and also revealed that Jupiter has multiple moons of its own.
Formerly the editor of his running club's newsletter, he has been published in "Trail Runner Magazine" and "Men's Health. See the resource for an interactive demonstration of this process. What Is Diffused Light? Characteristics of Plane Mirrors.
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