1. Lens Equation Word Problems
Seo
Physics

2. Word problem terminologies
1) Spherical center = radius of curvature
2) Focal point = half of the radius of curvature
3) Converging lens = convex lens
4) Diverging lens = concave lens
5) Double concave lens = concave mirror

3. Mirror equation review
Lens Equation? = do di f do di

4. Magnification review hi = -di = M do ho ho hi
Magnification ratio equation?
hi = -di = M ho do ho hi

5. Practice 1
An object is 3.3 cm high is 22.0 cm from a concave lens. The radius of curvature is 25 cm.
A) Draw the Ray Diagram
B) Image Characteristics
Image is Reduced, Real, and Inverted
3.3 cm hi
22 cm

6. di = 29.0 cm hi = -4.35 cm Practice 1 (con.) 1 + 1 = 1 do di f
An object is 3.3 cm high is 22.0 cm from a concave lens. The radius of curvature is 25 cm. (Focal length is half of the radius curvature. f= 12.5 cm). = do di f
C) Find the Image distance =
22 cm di
12.5 cm
= 0.08 cm cm
di = 29.0 cm
1/di= cm
hi = -di = M ho do
D) Find the height of the Image
hi = cm
hi = -di
x ho do
hi = cm
x 3.3 cm
22 cm

7. DIY
A bird 2.0 cm high is 30.0 cm from a concave lens. The radius of curvature is 20.0 cm.
A) Draw the Ray Diagram
B) Image Characteristics
Image is Reduced, Real, and Inverted
2 cm hi
30 cm

8. di = 15 cm hi = -1 cm DIY (con.) 1 + 1 = 1 do di f 1 = 1 - 1
A bird 2.0 cm high is 30.0 cm from a concave mirror. The radius of curvature is 20.0 cm (focal length is half of the radius curvature= 10 cm) = do di f
C) Find the Image distance =
30 cm di
10 cm
= 0.1 cm – 0.03cm
di = 15 cm
1/di= cm
hi = -di = M ho do
D) Find the height of the Image
hi = -1 cm
hi = -di
x ho do
hi = cm
x 2.0 cm
30 cm

9. Practice 2 hi ho 20 cm 15 cm B) Image Characteristics
A bird that is 5 cm high is placed 15 cm in front of a converging lens with focal length of 20 cm.
A) Draw the Ray Diagram ho hi
20 cm
15 cm
B) Image Characteristics
Image is Reduced, Inverted and Virtual

10. di = -58.82 cm hi = 19.60 cm Practice 2 (con.) 1 + 1 = 1 do di f
A bird that is 5 cm high is placed 15 cm in front of a converging lens with focal length of 20 cm. = do di f
C) Find the Image distance =
15 cm di
20 cm
= 0.05 cm – 0.067cm
di = cm
1/di= cm
hi = -di = M ho do
D) Find the height of the Image
hi = cm
hi = -di
x ho do
hi = cm
x 5.0 cm
15 cm

11. DIY hi ho 20 cm 35 cm B) Image Characteristics
A bird is 10 cm high and placed 35 cm in front of a converging lens with radius of curvature of 20 cm.
A) Draw the Ray Diagram ho hi
20 cm
35 cm
B) Image Characteristics
Image is Reduced, Inverted and Virtual

12. di = 14.28 cm hi = -4.08 cm DIY (con.) 1 + 1 = 1 do di f 1 = 1 - 1
A bird is 10cm high and placed 35 cm in front of a converging lens with radius of curvature of 20 cm. = do di f
C) Find the Image distance =
35 cm di
10 cm
= 0.1 cm – 0.03cm
di = cm
1/di= 0.07 cm
hi = -di = M ho do
D) Find the height of the Image
hi = cm
hi = -di
x ho do
hi = cm
x 10.0 cm
35 cm