The students will be able to identify the various types of lenses

1. Physics 1161 – Prelecture 23
Physics 1161 – Prelecture 23
Converging & Diverging
Converging & Diverging
Lenses
Lenses

2. Shape of a Lens
Shape of a Lens

3. Types of Lenses
Types of Lenses

4. Lens Terms
Lens Terms

5. Three Rays to Locate Image
Three Rays to Locate Image
 Ray parallel to axis bends through the focus.
 Ray through the focus bends parallel to axis.
 Ray through center of lens passes straight
through.

6. Characterizing the Image
Characterizing the Image
Images are characterized in the
following way
1. Virtual or Real
2. Upright or Inverted
3. Reduced, Enlarged, Same Size

7. Object Beyond 2f
Object Beyond 2f
Image is
– Real
– Inverted
– Reduced

8. Object at 2f
Object at 2f
Image is
– Real
– Inverted
– Same size

9. Object Between 2f and f
Object Between 2f and f
Image is
– Real
– Inverted
– Enlarged

10. Object at F
Object at F
No Image is Formed!

11. Object Closer than F
Object Closer than F
Image is
– Virtual
– Upright
– Enlarged

12. Converging Lens Images
Converging Lens Images

13. Concave (Diverging) Lens
Concave (Diverging) Lens
 Ray parallel to axis
refracts as if it comes
from the first focus.
 Ray which lines up with
second focus refracts
parallel to axis.
 Ray through center of
lens doesn’t bend.

14. Image Formed by Concave Lens
Image Formed by Concave Lens
Image is always
– Virtual
– Upright
– Reduced

15. Concave Lens Image
Concave Lens Image
Distance
Distance
 As object distance
decreases
– Image distance
decreases
– Image size increases

16. Image Characteristics
Image Characteristics
 CONVEX LENS – IMAGE DEPENDS ON
OBJECT POSITION
– Beyond F: Real; Inverted; Enlarged, Reduced, or
Same Size
– Closer than F: Virtual, Upright, Enlarged
– At F: NO IMAGE
 CONCAVE LENS – IMAGE ALWAYS SAME
– Virtual
– Upright
– Reduced

17. Lens Equations
Lens Equations
 convex: f > 0; concave: f < 0
 do > 0 if object on left of lens
 di > 0 if image on right of lens
otherwise di < 0
 ho & hi are positive if above
principal axis; negative below
1 1 1
o i
f d d
 
i i
o o
h d
M
h d
 
do
di