MAGNIFYING GLASS

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# MAGNIFYING GLASS - PowerPoint PPT Presentation

How can a teacher increase the size of her pay check? By looking at it through a magnifying glass . MAGNIFYING GLASS. By: Toni-Ann Smith and Thomas Bailey. A magnifying glass is…. An instrument made of a convex lens that enlargers an image and focuses light.

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How can a teacher increase the size of her pay check?By looking at it through a magnifying glass.

MAGNIFYING GLASS

By: Toni-Ann Smith and Thomas Bailey

A magnifying glass is…
• An instrument made of a convex lens that enlargers an image and focuses light.
• The magnifying glass is biconvex meaning that both sides of the glass are convex, where the two sides of the glass are thicker in the middle than on the outer edges.
• The glass is usually held in a frame with a handle

Also called converging lens.

• A lens that curves outwards.
• They are used for close examinations of smaller objects.
• When rays of light approach the glass it refracts and the light bends towards a focal point.
• When the object distance gets closer to the focal point, the image is enlarged
Convex lens
The object under the center of the magnifying glass will appear larger while the objects outside the edge of the glass will look smaller. This is because when you look through the glass you are focusing on one point.

Bacon was born in 1214 in a small village in Somerset.He studied optics at Oxford in Paris and became a professor there. He is credited with the invention of the magnifying glass because of his inputs and curiosity with optics. His greatest contribution dealt with lens, reflection and refraction.

Roger Bacon

Invention

How it works
• As light enters the convex lens it bends. The object will appear larger in our eyes, but has not actually changed in size.
• The lens will magnify an object if the object is closer to the lens than the focal point.
Making the Connection...
• As mentioned in class, the index of refraction of a converging lens is different compared to air.
• As rays of light enters the lens it will bend towards the normal (focal point) and then bend away from the normal as it leaves the glass.
• An image forms through the converging lens when rays of light from the object are focused on one part of the lens. All the light is focused at the focal point.
• The focal point is where the rays all intersect after going through the lens. That is where the image will form.
Still Connecting…
• To draw the rays for a convex lens you first draw a ray from the top of the object to the top of the lens and then it will bend towards the focal point as it exits the lens. The second ray should be drawn from the object to the center of the lens and continue in the same direction. The third ray is drawn from the object l through the focal point and then parallel.
• Where all the rays meet up is where the image will be located, at the focal point.
Real vs. virtual
• The image will be virtual if the distance of the object is less than the focal length.
• To have a virtual image that the image is on the same side of the lens as the object and you cant touch it. It is not inverted and much larger than the object.
• Depending on the distance the lens is from the object and the distance from the lens to the focal point, the image will either be real or virtual.
• The image will be real, and inverted if the focal length is less than the distance of the object. It will be larger is the distance form the object to the lens is less than twice the focal length and vice versa for a smaller image
A New Insight

Shortly after Bacon made the magnifying glass, the first convex eyeglasses were being made in Europe. The invention of the magnifying glass and more discoveries about the convex lens lead to the invention of binoculars (useful for bird watching or upper level seats at beaver stadium), microscopes (which helped revolutionize the fields of chemistry and biology), and telescopes (which help astronomy and allows me to view spectacular images courtesy of NASA’s powerful scopes.

I'm astonished at how many different things have stemmed form the invention of the magnifying glass, and how much of our daily lives involve some sort of by-product from the study and invention of convex lens and the magnifying glass

insight
• It’s amazing how so many people (and me before this class) can tell you that a magnifying glass can enlarge an object of image, but they do not know why. Now, whenever I look through a magnifying glass I will be able to explain how and why it works.
Just Glass Site. (2011) Retrieved November 18, 2011, from: http://justglasssite.com/tag/magnifying-glass-2

BUYUTEC Lens Lupa magnifying glass [deviantART]. (2010) Retrieved November 28, 2011, from: http://kavsikuzah.deviantart.com/journal/BUYUTEC-Lens-Lupa-magnifying-glass-222678733

Jokedictionary.com. (2000-11) Retrieved November 28, 2011, from: http://www.jokedictionary.com/jokes/m/magnifyingglass.html

Gilles Tran (image creator). (2011). Ray Tracing Magic [Introduction: The “Information Field” beneath Our Reality], Retrieved November 28. 2011, from: http://blog.world-mysteries.com/science/ray-tracing-magic/

GNU Free Documentation License, Biography Base. (2011). Roger Bacon Biography. Retrieved November 28, 2011, from: http://www.biographybase.com/biography/Bacon_Roger.html

Works Cited

Icosics: Lens. (2010) Retrieved November 30, 2011, from: http://icosics.blogspot.com/2010/04/lens-and-optical-instruments.html

Lecture13A, Optics. Written by Dr. Drew, Kirstin P. (2011) Department of Physics, The Pennsylvania State University, University Park, PA.

Lecture13B, Lenses/Project Day. Written by Dr. Drew, Kirstin P. (2011) Department of Physics, The Pennsylvania State University, University Park, PA.

Wikipedia Foundation Inc. 2011, November 28. Roger Bacon. Retrieved November 28, 2011, from: http://en.wikipedia.org/wiki/Roger_Bacon

Elizabeth Stover, eHow, Demand Media. (1999-2011) Who Invented the Magnifying Glass? Retrieved November 28, 2011 from: http://www.ehow.com/facts_5031039_invented-magnifying-glass.html

Diana Doherty, eHow, Demand Media. (1999-2011) How Does a Magnifying Lens Work? Retrieved November 28, 2011, from: http://www.ehow.com/how-does_4568247_magnifying-lens-work.html