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.htm
Type of Image
Real or Virtual
Enlarged or Reduced
Erect or Inverted
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
do + object distance
di + real image
di - virtual image
hi + erect image
hi - inverted image
f + converging lens (convex) f - diverging lens (concave)
Magnification
M = hi = -di
ho do
Note: When magnification is <0, the image is inverted.
Lens Equation
1 = 1 + 1 f do di
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.