RAY DIAGRAMS FOR LENSES

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RAY DIAGRAMS FOR LENSES
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CONVEX (CONVERGING) LENS
All ray diagrams start with a center line and the
lens
Note the lens can be simplified into a straight
vertical line
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Next, put in the focal points (F) -- Note for
lenses there are 2 focal points.
The center is located where the lens intersects
the center line
Next, put in the object as described in the
problem.
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You can get 3 types of images from a convex
(converging) lens. The type of image is
determined by the object distance.
do gt 2 f
IMAGE real, inverted, smaller
F
F
2 f gt do gt f
IMAGE real, inverted, bigger
do lt f
IMAGE virtual, upright, bigger
F
F
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RAY DIAGRAM do gt 2 f
- draw a ray through near F to the lens THEN
parallel to the center line
- draw a ray parallel to the center line to the
lens THEN through opposite F
- draw a ray through C
The point where the refracted rays intersect is
where the image will be formed
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RAY DIAGRAM 2f gt do gt f
- draw a ray through near F to the lens THEN
parallel to the center line
- draw a ray parallel to the center line to the
lens THEN through opposite F
- draw a ray through C
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RAY DIAGRAM do lt f
- draw a ray in line with near F to the lens THEN
parallel to the center line
- draw a ray parallel to the center line to the
lens THEN through opposite F
- draw a ray through C
Refracted rays do not meet in real space. Draw
dotted lines back from reflected rays so that
they intersect behind the lens
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CONCAVE (DIVERGING) LENS
All ray diagrams start with a center line and the
lens
Note the lens can be simplified into a straight
vertical line
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Next, put in the focal points (F) -- Note for
lenses there are 2 focal points.
The center is located where the lens intersects
the center line
Next, put in the object as described in the
problem.
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You can only get 1 type of image from a concave
(diverging) lens virtual, upright, smaller
- draw a ray in line with opposite F to the lens
THEN parallel to the center line
- draw a ray parallel to the center line to the
lens THEN in line with near F
- draw a ray through C
Refracted rays do not meet in real space. Draw
dotted lines back from refracted rays so that
they intersect behind the lens.