LensesLenses

Lenses are curved surfaces that refract light as it passes through.

[http://www.ast.cam.ac.uk/~optics/dazle/photos/finished_lenses/lenses_1_to_4_1.jpg]

Convex LensesConvex Lenses

Thicker in the middle than at the edges

Bends light toward the middle. (Focal Point!)

[http://www.bbc.co.uk/scotland/education/bitesize/standard/img/physics/waves/convex_lens.gif]

Can correct farsightedness.

[http://www.schools.net.au/edu/lesson_ideas/optics/images/optic_hyperopia.gif]

Convex LensesConvex Lenses

Can be used to create magnified virtual images.

Object must be less than 1 focal length away

[http://sol.sci.uop.edu/~jfalward/physics17/chapter12/magnifier2.jpg]

Convex Lens Ray DiagramConvex Lens Ray DiagramObject Distance < 1 focal length away from lens

Virtual Image: Magnified &

Upright

Convex LensesConvex Lenses

Can create real images if the object is > 1 focal length away.

[http://gpc.edu/~pgore/PhysicalScience/ray_diagram_sample.jpg]

Object Real Image

Click for Images Demonstration

Convex Lens Ray DiagramConvex Lens Ray DiagramObject Distance > 1 focal length away from lens

Real Image: Upside Down

(But Size Varies!)

Concave LensesConcave Lenses

Thicker on the edges than they are in the middle.

Bends light outward (no focal point!)

[http://www.bbc.co.uk/scotland/education/bitesize/standard/img/physics/waves/convex_lens.gif]

Can correct nearsightedness.

[http://www.schools.net.au/edu/lesson_ideas/optics/images/optic_hyperopia.gif]

Concave LensesConcave Lenses

Creates only a smaller virtual image.

[http://sol.sci.uop.edu/~jfalward/physics17/chapter12/magnifier2.jpg]

Concave Lens Ray DiagramConcave Lens Ray DiagramObject Located Anywhere

Virtual Image: Smaller &

Upright