# Lenses. What phenomenon is evident in lenses? https://wiki.brown.edu/confluence/display/PhysicsLabs/PHYS+0080+BC.

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Lenses

What phenomenon is evident in lenses? https://wiki.brown.edu/confluence/display/PhysicsLabs/PHYS+0080+BC

Basic Types of Lenses Convex Concave

Convex Lens http://www.shokabo.co.jp/sp_e/optical/labo/lens/lens.htm

Concave Lens http://www.shokabo.co.jp/sp_e/optical/labo/lens/lens.ht m

Type of Image Real orVirtual Enlarged or Reduced ErectorInverted

Convex (Converging) Lens Center C f

Ray Diagram for Convex Lens Principal Axis http://facstaff.gpc.edu/~pgore/PhysicalScience/ray_diagram_sample.jpg

Rules for Ray Diagrams for Convex Lens A parallel ray refracts through the focal point. A ray through the center of the lens continues straight. A ray coming through the focal point, refracts parallel to the principal axis.

Summary for Convex Lens When the object is: Beyond 2F At 2F Between 2F and F At F Between F and lens Then the image is: Between 2F and F At 2F Beyond 2F No image Virtual image

Sign Convention d o + object distance d i + real image d i - virtual image h i + erect image h i - inverted image f + converging lens (convex) f - diverging lens (concave)

Magnification M= h i = -d i h o d o Note: When magnification is <0, the image is inverted.

Lens Equation 1 = 1 + 1 f d o d i

Concave (Diverging) Lens Object Image

Summary for Concave (Diverging) Lens Always: virtual, reduced, upright image

Notice! The art of drawing ray diagrams has not changed drastically. The equations for image formation in LENSES are the same as the equations for image formation in MIRRORS.

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