1 2016/6/13 Ch.12 Linear Magnification ( 放大率 ) magnification m = height of image (image size) height of object (object size)

2 2016/6/13 Class Exercise 12.1 Mary uses a convex lens to examine the print on a piece of paper. The image of the letters “ CS ” is as shown. What is the linear magnification of the image?

3 2016/6/13 Class Exercise 12.1 Mary uses a convex lens to examine the print on a piece of paper. The image of the letters “ CS ” is as shown. What is the linear magnification of the image? m = 3

4 2016/6/13 LPSMC / / S3 / IS(1) magnification ( 放大率 ) m > 1 means the image is magnified ( 放大 ). m = 1 means the size of image is equal to the size of object ( 大小一樣 ). 0 < m < 1 means the image is diminished ( 縮小 ).

5 2016/6/13 Class Exercise 12.2 Peter uses a convex lens to examine the print of height 5 mm on a piece of paper. What is the linear magnification when the height of image is (a) 10 mm ? (b) 2 mm ?

6 2016/6/13 Class Exercise 12.2 Peter uses a convex lens to examine the print of height 5 mm on a piece of paper. What is the linear magnification when the height of image is (a)10 mm ? (b)2 mm ? (a) m = 10 mm / 5 mm = 2 (b) m = 2 mm / 5 mm = 0.4

7 2016/6/13 Class Exercise 12.3 (a) Magnification = ?

8 2016/6/13 Class Exercise 12.3 (a) Magnification = 10 / 5 = 2

9 2016/6/13 Class Exercise 12.3 (b) Magnification = ?

/6/13 Class Exercise 12.3 (b) Magnification = 4 / 10 = 0.4

/6/13 Linear Magnification ( 放大率 ) magnification m = image distance ( 像距 ) object distance ( 物距 )

/6/13 Class Exercise 12.4 (a) Magnification = ?

/6/13 Class Exercise 12.4 (a) Magnification = 20 / 10 = 2

/6/13 Class Exercise 12.4 (b) Magnification = ?

/6/13 Class Exercise 12.4 (b) Magnification = 10 / 25 = 0.4

/6/13 Class Exercise 12.5 height of object = 10 cm object distance = 60 cm image distance = 30 cm

/6/13 (a) What type of lens is used in the experiment? (b)Draw the image seen by the eye on the screen in the diagram. (c) Calculate the linear magnification of the images.

/6/13 (a)What type of lens is used in the experiment? Convex lens (b)Draw the image seen by the eye on the screen in the diagram. (c) Calculate the linear magnification of the images. m = 30 cm / 60 cm = 0.5

/6/13 (d) Use a ray diagram to find the focal length of the lens.

/6/13 (d) Use a ray diagram to find the focal length of the lens. f = 20 cm 60 cm 30 cm

21 Homework: Assignment Book 1. Chapter 12 Linear Magnification Q. 1 – Q.4 (p.21-25) 2. Deadline: ___