Lens Ray Diagrams 2 types of lenses just

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Lens Ray Diagrams 2 types of lenses just like mirrors Convex Lens - Converging

Lens Ray Diagrams 2 types of lenses just like mirrors Convex Lens - Converging - thick in middle, thin edge - Opposite of mirror Concave Lens - Diverging - thin in middle, thick edge

General Information for all lenses • The principle axis still exists line parallel to

General Information for all lenses • The principle axis still exists line parallel to center of lens • The focal point is no longer 1/2 distance from CC • The focal point depends on both curvature and the way the lens refracts light • There are 2 focal points. f 1 and f 2 - one on each side of lens • The ray method for lenses is similar to mirrors.

Ray Diagrams: Convex Lens • Ray #1: Light travels parallel & refracts through focal

Ray Diagrams: Convex Lens • Ray #1: Light travels parallel & refracts through focal point f 2 • Ray #2: Light travels straight through the center of the lens • Ray #3: Light travels through first focal point(f 1) & refracts parallel to the principle axis

• Object at infinity - image located at f 2. This is one

• Object at infinity - image located at f 2. This is one way to find the focal point 1 1 2 2

Object located beyond 2 f 1 - image is located between f 2 and

Object located beyond 2 f 1 - image is located between f 2 and 2 f 2 …Image real, inverted, smaller 1 1 2 2

Sample problem A 3 cm object is located 12 cm from a convex lens

Sample problem A 3 cm object is located 12 cm from a convex lens with a focal length of 3 cm. Where would the image be located? What is the size of the image?

Image Location Given: So=3 cm do=12 cm f=3 cm 1/di + 1/do = 1/f

Image Location Given: So=3 cm do=12 cm f=3 cm 1/di + 1/do = 1/f 1/di = (1/f)-(1/do) 1/di = (1/3) - (1/12) 1/di = 4/12 - 1/12 = 3/12 di = 12/3 = 4 cm

What is the size of the image? si/so = -di/do si = -so di

What is the size of the image? si/so = -di/do si = -so di /do - 4 cm (3 cm) /12 cm = -1 cm

Object located @ 2 f 1 - image is located at 2 f 2

Object located @ 2 f 1 - image is located at 2 f 2 …Image real, inverted, same size 1 1 2 2

Object located between 2 f 1 & f 1 - image is beyond 2

Object located between 2 f 1 & f 1 - image is beyond 2 f 2 … Image real, larger, inverted 1 1 2 2

Object located at f 1 Rays refracted parallel - No Image 1 1 2

Object located at f 1 Rays refracted parallel - No Image 1 1 2 2

Object located closer than f 1 … Trace diverging rays backwards Image is erect,

Object located closer than f 1 … Trace diverging rays backwards Image is erect, larger and virtual 1 1 2 2

Ray Diagrams: Concave (Diverging) Lens 1 st Ray: Parallel to the Principle axis, as

Ray Diagrams: Concave (Diverging) Lens 1 st Ray: Parallel to the Principle axis, as if it had come from the 1 st focal point (f 1) 2 nd Ray: Straight through the center of the lens 3 rd Ray: Heads toward 2 nd focal point (f 2) & refracts parallel

Object at infinity - image located at f 1 and is virtual 1 1

Object at infinity - image located at f 1 and is virtual 1 1 2 2

Object located @ 2 f 1 ……Image is virtual, upright, smaller 1 1 2

Object located @ 2 f 1 ……Image is virtual, upright, smaller 1 1 2 2

Object located between 2 f 1 and f 1 ……Image is virtual, upright, smaller

Object located between 2 f 1 and f 1 ……Image is virtual, upright, smaller 1 1 2 2

Object located @ f 1 ……Image is virtual, upright, smaller 1 1 2 2

Object located @ f 1 ……Image is virtual, upright, smaller 1 1 2 2

Concave (Diverging) Lens • Always form images that are Virtual Upright Smaller

Concave (Diverging) Lens • Always form images that are Virtual Upright Smaller