Unit 8 Lesson 7 Convex Lenses concave convex
- Slides: 16
Unit 8, Lesson 7 Convex Lenses
concave convex (Diverging) lens (Converging) lens
Convex (converging) lens Principle axis f f
Image through a convex lens Try This: Describe the image if do = 1. 5 f and f = 20 cm. do = 30 cm f Image Characteristics: size – larger location – further type – real attitude – inverted f
Image through a convex lens Try This: Describe the image if do = 0. 5 f and f = 20 cm. do = 10 f Image Characteristics: size – larger location – further type – virtual attitude – upright f
Brain Break!
convex lens calculations Example: Describe the image if do = 1. 5 f and f = 20 cm. do = 30 cm 1 = 1 + 1 f do di 1 = 1 + 1 20 30 di 1 = 1 - 1 = di 30 20 1 = f M = hi = -di do ho 1 60 di = 60 cm M = -di = do -60 30 1 + 1 do di = - 2 X Image Characteristics: size – bigger location – 60 cm opposite type – real attitude – inverted
convex lens calculations Try This: Describe the image if do = 0. 5 f and f = 20 cm. do = 10 cm 1 = 1 + 1 f do di 1 = 1 + 1 20 10 di 1 = 1 - 1 = 1 di 10 20 -20 1 + 1 do di M = hi = -di do ho Image Characteristics: di = -20 cm M = -di = do 1 = f -(-20) = 2 X 10 size – bigger location – 20 cm on same side type – virtual attitude – upright
Homework: • Pg. 252 #5 and 6
Unit 8, Lesson 8 Concave Lenses
Concave (Diverging) lenses f
Ray Rules for concave lenses Principle axis f f
Try This: Locate and characterize an image formed in a diverging lens of focal length 10 cm if do = 15 cm. (Show using a ray diagram + equations. ) f f 1 = 1 + 1 f do di 1 = 1 + 1 -10 15 di 1 = 1 - 1 = di 15 -10 M = -di = do Image Characteristics: 1 -6 di = -6 cm -(-6) = +0. 4 X 15 size – smaller location – 6 cm on same side type – virtual attitude – upright
Brain Break!
Example: Where should an object be placed if an upright virtual image half its size is to be formed by a concave lens of focal length 10 cm? 1 = -10 1 + 1 do di M = -di = 1 do 2 di = -0. 5 do 1 = 1 + 1 -10 do -0. 5 do 1 = 1 - 2 = do do -10 do = 10 cm f -1 do
Homework: • Optics Review sheet!
